Becoming a parent only further stretches our already-too-thin sleep allotments. Newborn babies wake frequently to feed or for comfort during the night. We try to “sleep when the baby sleeps” and piece it together to come up with a reasonable amount, but it often doesn’t feel sufficient. And now more than ever, new parents are really isolated as they make this transition; they don’t have much in the way of backup resources to help with the 24/7 job of caring for a baby.

This month, the theme of our Carnival of Evidence-Based Parenting is Transition to Parenthood. (See the bottom of this post for links to other Carnival posts and here for summaries of them all.) Sleep deprivation is a universal part of that transition. What does the sleep deprivation of early parenthood really look like? How does it affect us? And what can we do to mitigate it?

Just How Bad Is It?

For many moms, sleep debt actually begins in pregnancy, when sleep needs may increase but discomfort and frequent trips to the bathroom interfere with a full night’s sleep. But by far, the biggest change happens in the immediate postpartum period. One study found that in the first week of the baby’s life (compared with late pregnancy), moms got 1.5 hours less sleep, fragmented into three times more sleep episodes per day. The early postpartum period is also characterized by lots of day-to-day variability in sleep. Sleeping with a new baby means unpredictability, with little to no control over whether tonight will be a good night or a bad one.

Mothers usually get the majority of our sympathy when it comes to postpartum sleep deprivation, but the research shows that fathers’ sleep takes a hit, too. A study of 72 San Francisco couples welcoming their first baby compared sleep in the last month of pregnancy to sleep in the first month postpartum (around 20 days of life).  Across this time span, mothers lost an average of 41 minutes of nighttime sleep, while dads lost just 18 minutes. Moms, however, gained 30 minutes per day in daytime napping; dads didn’t get a nap bump at all. In fact, in this study, dads actually slept less than moms – both in late pregnancy and in the postpartum period. Moms still had it harder; they were waking more during the night and had more sleep fragmentation than dads (and it’s quite possible that moms need more sleep, what with recovery from childbirth and the demands of breastfeeding). But regardless, in this and other studies, moms and dads both reported a similar level of fatigue during the day.

There’s some good news to come out of this research, however. It seems that experienced moms are better at handling sleep in the postpartum period. Despite juggling more responsibility at home, studies show that moms who had given birth at least once before tended to get more sleep at all stages of pregnancy and in the postpartum period. Their sleep was also more efficient, meaning that of the time they spend in bed, they spend most of it sleeping rather than tossing and turning – or laying awake listening to the grunts and sighs of new baby sleep. Somehow, experienced moms seem to prioritize sleep more, or they’re just so tired that they crash hard at every opportunity.

How does sleep deprivation affect new parents?

We know a lot about the effects of sleep deprivation but actually very little about the specific type of crap sleep experienced by new parents. Most sleep deprivation studies have been conducted in residential labs, where participants (often young, probably resilient, undergrads) are generally paid to live for a few nights or maybe weeks so that their sleep habits can be controlled and monitored. In a review paper entitled “Sleep Disruption and Decline in Marital Satisfaction Across the Transition to Parenthood,” Gonzaga professor Anna Marie Medina and colleagues make an important point: Lab study participants know that they’ll be subjected to sleep deprivation for a finite amount of time, and they know they can even drop out if it becomes too much for them.

“Understanding that one can end a study, and being certain of the temporal parameters of potential sleep deprivation, imbues the experience of sleep loss with a level of controllability that new parents seldom have. That is, (most) new parents realize they cannot opt out of the sleep disruption experience, and they have no certainty about when they may have an opportunity for sufficient sleep. The stress literature has suggested that such uncontrollability could amplify the mood and physiological consequences of sleep deprivation.”

In other words, most of what we know about the effects of lost sleep may be even worse in new parents. On that happy note, there are a few major areas of concern…

Sleep deprivation impacts mood.

Medical residents are notorious for being sleep-deprived, and their situations may be similar to new parents in that their sleep is chronically restricted and fragmented. Studies on medical residents show that sleep loss is associated with more intense negative emotions and hostility. One study found that interns who became chronically sleep-deprived over the course of their first year of training had seven times the odds of becoming moderately depressed, compared to those managing to get enough sleep. Reading these studies, all I could feel was sympathy for my friends who juggled residency and new parenthood at the same time.

Specific to new moms, many studies show that moms whose babies have sleep problems are at greater risk for postpartum depression. In studies that have given parents advice in managing their baby’s sleep, resulting in improved sleep for the baby, maternal mood improves as well.

Sleep deprivation impacts cognitive function.

Sleep deprivation decreases a range of cognitive abilities, and I’m not just talking about SAT scores. For example, reaction time and alertness are essential for safe driving. Working memory is the ability to juggle multiple tasks, and well, that’s what parents do. Cognitive flexibility is what allows you to see a situation from more than one point of view (a skill vital to both parenting a toddler and maintaining a healthy marriage) or to quickly switch tasks, maybe from trying to fire off a work email to the more urgent demands of a toddler who has to go potty NOW. Verbal fluency is the ability to find the right word at the right time – to communicate effectively. We use all of these skills throughout our daily lives. They allow us to work towards goals (even mundane ones like getting out the door or getting dinner on the table), solve problems, and regulate emotions. And guess what? All of these cognitive skills are impaired by sleep deprivation.

To put this into perspective, one study found that two weeks of six hours of sleep per night caused declines in many cognitive measures – similar to those found after a full 24-48 hours of sleep deprivation. Perhaps more concerning is that the six-hour sleepers had no idea how impaired they were; they rated their sleepiness as only mild, but their test performance showed otherwise. Another study found that cognitive performance of people who had been awake for 18-19 hours was comparable to those with blood alcohol content (BAC) of 0.10 (the legal limit for driving in most U.S. states is 0.08). It is estimated that 15-33% of fatal car crashes are related to driver fatigue.

What can you do to improve your sleep situation?

I know that you know that sleep deprivation sucks, and I don’t mean for this post to be a downer. Is there anything we can we do to make things better? I can’t claim to have answers, but I’ll offer some suggestions:

Cut yourself some slack. This parenting job is hard enough as it is. Doing it on little sleep everyday? It’s a hurculean task, and yet we do it. Sometimes we need to just focus on the basics and have popcorn for dinner.

Prioritize sleep. It’s so critical to our health and happiness. The dishes in the sink? They aren’t nearly as important.

Give yourself a bedtime. We know our kids don’t function well if they’re short on sleep. We don’t either – we’re just a little better at hiding it.

Get help. This is particularly critical for parents of newborns. It may require creative delegation of tasks to friends and family so that you can squeeze in a longer nap or an earlier bedtime. They’re happy to help, and you need it. We were never meant to parent alone.

Help your baby develop healthy sleep patterns. Check out my tips for newborn sleep here. And if your older baby is struggling with sleep (and by extension, you are too), know that it is not selfish to make changes that help everyone get the rest they need (more on that here).

Avoid screen time before bed. It gets in the way of melatonin release, confusing the biological clock trying to keep time in our brains and prepare us for sleep. Yes, your Facebook feed may be your lifeline to the world, but it could also be keeping you up at night.

Be aware of your sleep debt. I think that after a while, we forget how much sleep we’re missing. Six hours a night and chronic daytime yawns become our new normal. But knowing that we’re behind on sleep, combined with the knowledge of the profound effects of sleep debt on mood and cognition, can give us valuable perspective. Maybe, for example, your partner is being just a little bit of an ass instead of the complete asshole that you perceive. Maybe catching up on sleep will help the day’s problems seem a little more manageable.

And now, a confession: All of these tips I just gave you? I’m not very good at them. I hate leaving dishes in the sink, and I’m not good at asking for help. I stay up too late – usually in front of my computer. I don’t get enough sleep, and it isn’t even my daughter’s fault. She sleeps for 11 hours at night. Why can’t I manage to sleep for 8 of those? What am I staying up for? It’s that treasured ME time. These days, most of it is actually spent working, but that doesn’t make it easier for me to give any of it up. This research, though, has convinced me that sleep deprivation is probably putting a damper on my productivity, and maybe my parenting patience.

So, I’m taking a pledge: For the rest of the month of May, in honor of Mothers’ Day, I’m giving myself at least 7 hours of sleep each night. I’m making it a priority. I’m informing my husband that no, I will not watch one more episode of Breaking Bad with him, unless it is before 10 PM. And I’m turning off my computer and phone by that time, too. It’s a personal experiment and a gift to myself. Happy Mother’s Day, Me!

Do you get enough sleep? If so, how do you do it? If not, what’s standing in your way?

Check out the other posts in this second edition of the Carnival of Evidence-Based Parenting:

The Transition to New Motherhood (Momma, PhD)

Bonding in Early Motherhood:  When Angels Don’t Sing and the Earth Doesn’t Stand Still (Red Wine and Applesauce)

The Connection Between Poor Labour, Analgesia, and PTSD (The Adequate Mother)

For Love or Money:  What Makes Men Ready for New Fatherhood (Matt Shipman)

What the Science Says (and Doesn’t Say) About Breastfeeding Issues, Postpartum Adjustment, and Bonding (Fearless Formula Feeder)

No, Swaddling  Will Not Kill Your Baby (Melinda Wenner Moyer,  Slate)

Sleep Deprivation:  The Dark Side of Parenting (Science of Mom)

The Parenting Media and You (Momma Data)

Reassessing Happiness Research:  Are New Parents Really That Miserable? (Jessica Smock)

40 Long Days and Nights (Six Forty Nine)

You can also “like” the Carnival of Evidence-Based Parenting on Facebook. Check out our Facebook page, and connect with all of us there! And finally, we’ll be hosting a Twitter party (I’m @scienceofmom) Friday 1-2 PM EST to discuss new parenthood and our posts (#parentscience). Please join us!

But then the baby arrives, and your world changes forever. Sleep disruption is one of the most immediate and dramatic changes associated with parenthood. It isn’t just that you’re getting less sleep; it’s that your sleep is suddenly dependent on this baby sleeping. And even though newborns sleep a lot – as much as 16-18 hours per day – it feels disorganized and unpredictable.

The thing is, babies, even brand new ones, actually do have organized sleep, it just isn’t organized like yours. But under the surface, baby is working towards being more like you in his sleep. During the first few months, you have no choice but to go with the flow and sleep when the baby sleeps (something I was never good at), but it can help to understand the inherent patterns in your baby’s sleep/wake cycles so that they become more predictable. Your goal is to work with your baby’s biology, find some time for your own sleep, and support your baby in his natural development towards more mature sleep patterns.

In the research for my book, I’ve buried myself in research papers on infant sleep, trying to glean some knowledge that can be helpful to parents in these first few months of baby’s life. Here’s what I’ve come up with so far:

1. Understand newborn sleep cycles. Newborn sleep alternates between active and quiet sleep (akin to REM and non-REM sleep in adults). During the first few months of life, infants usually begin each sleep period in active sleep. Then, after about 25 minutes, they’ll transition to a cycle of quiet sleep, also about 25 minutes long. During active sleep, babies will twitch and flail their limbs, grunt and sigh, and maybe even cry a little. Their eyes move beneath translucent closed lids and may even open from time to time. In quiet sleep, babies breathe slowly and rhythmically, and their bodies are still ^1,2.

Why care about the biology of sleep? Because it can help you in these practical ways:

• Babies wake easily from active sleep, so if your baby falls asleep in your arms, wait until you see signs of that deeper, quiet sleep before you try to move him.
• Around the 45-50 minutes mark, baby will be finishing up that first active/quiet sleep cycle of 45-50 minutes. Transitioning from one cycle to the next can be tricky for a new baby, so if he wakes during this time (particularly if it’s after just one cycle), see if he wants your help returning to sleep before assuming that he’s ready to eat or play.
• Active sleep is noisy. Parents often mistake the normal vocalizations of active sleep as the baby waking, and in their efforts to soothe the baby, they’ll actually wake him up. If you think your baby is waking up, pause and watch him for a moment. He may just be dancing in his sleep, or he might be waking briefly only to return to sleep on his own.

2. Help your baby find a rhythm. We are adapted to Earth’s 24-hour cycle of light and dark, and our physiological circadian rhythms help us to feel awake during the day and sleepy at night. Newborn babies, on the other hand, sleep just as much during the day as they do at night. It takes them some time to develop rhythms to match our day/night cycle. You can help by sending baby strong environmental and social cues about day and night.

During the day, keep the baby in a light, maybe even noisy place, even as he naps. At night, keep the lights as low as possible and the environment quiet. Even as you’re feeding frequently during the night (and you probably are), keep your interactions with your baby very quiet, uninteresting, and unstimulating. Be boring. With these cues, babies start to show physiological circadian rhythms quickly. A rhythm in body temperature can be detected around one week of age, and by two months of age, babies have robust rhythms of the hormones melatonin and cortisol. By two to three months, most babies are sleeping for most of the night (just waking briefly to feed) and have some distinct periods of wakefulness during the day (with some naps, of course)^3–6. One study reported an outlier – a baby that hadn’t developed a day/night circadian rhythm at five months. Turns out that night owl took his night feedings in a brightly lit room – he had received confusing signals about nighttime⁷.

3. Start to develop a soothing bedtime routine. It’s never too early for this. Find some calming rituals that you repeat each night before bed. These become part of the social cues that will key your baby into the nighttime rhythm and let her know that sleep time is coming. Tell your baby what is happening: It’s almost time for bed, so we’re having a bath. Then you’ll have some milk, and I’ll sing our bedtime song. And then it will be time to sleep. (Bedtime routines have been shown to help babies fall asleep faster and get more sleep during the night, but they’ve only been empirically tested in older infants⁸. I just think it’s smart to start this within the first few months.)

4. If you’re breastfeeding, breastfeed at night. During pregnancy, baby was exposed to mom’s day/night rhythm of melatonin, which increases during the dark night and decreases during the light of day. If you breastfeed, you keep sending that sleepy melatonin signal to your baby through your milk, even before he begins to produce his own melatonin. Human breast milk reflects maternal plasma melatonin concentrations, peaking between midnight and 4 AM and being virtually undetectable during the day^9–11. Melatonin during a night feeding should help baby transition peacefully back to sleep. Consider this if you supplement with formula or use pumped breast milk for a nighttime bottle. Nighttime breast milk (pumped or from the breast) might mean better sleep for baby.

5. Let your baby practice falling asleep in different ways. You’re going to want to hold him a lot, and so will all his doting family. There is nothing like watching a newborn fall asleep in your arms. He’ll also fall asleep feeding. You might enjoy having him sleep on your chest in a wrap or sling while you go about your day. Enjoy all of these snuggles with your baby. But every once in a while, see if you can put him down sleepy but awake. Some, but not all, babies can be surprisingly flexible during the first months of life about how they sleep. Letting him practice this now may give your baby the skills he needs to sleep well later. Babies that are able to fall asleep without a lot of active soothing (i.e. feeding, rocking, bouncing, walking, driving) tend to be the same babies who sleep well during the night¹². This is a great time to encourage flexibility while also providing secure and predictable routines.

6. Observe your baby. Observing your baby means learning his particular signals for when he’s feeling sleepy; then you can work together towards getting comfortable for sleep. Observing your baby may mean that when you hear him start to grunt and move around during the night, you wait a moment and watch to see what he’s doing and if he’s trying to communicate with you. Is he hungry? Uncomfortable? Wet? He’ll let you know that. But he may just be transitioning from one sleep cycle to the next. He may want to go right back to sleep, or he may not have woken at all but instead is in a noisy active sleep period. Babies that learn to transition between sleep cycles without your help will grow into better sleepers later in infancy, but you have to give them a chance to practice this valuable skill^12–14. Wait a moment or two to see if he needs your help, and if he does, soothe him quietly.

What advice do you have for helping babies and parents find their groove with sleep?

REFERENCES:

1. De Weerd, A. W. & van den Bossche, R. A. S. The development of sleep during the first months of life. Sleep Med. Rev. 7, 179–191 (2003).

2. Anders, T., F. in Encycl. Early Child. Dev. (Tremblay, R. E., Boivin, M. & Peters, Rd.) 1–8 (Centre of Excellence for Early Childhood Development and Strategic Knowledge Cluster on Early Child Development, 2010). at

3. McGraw, K., Hoffman, R., Harker, C. & Herman, J. H. The Development of Circadian Rhythms in a Human Infant. Sleep 22, 303–310 (1999).

4. Mirmiran, M., Maas, Y. G. . & Ariagno, R. L. Development of fetal and neonatal sleep and circadian rhythms. Sleep Med. Rev. 7, 321–334 (2003).

5. Custodio, R. J. et al. The emergence of the cortisol circadian rhythm in monozygotic and dizygotic twin infants: the twin-pair synchrony. Clin. Endocrinol. (Oxf.) 66, 192–197 (2007).

6. Ardura, J., Gutierrez, R., Andres, J. & Agapito, T. Emergence and Evolution of the Circadian Rhythm of Melatonin in Children. Horm. Res. 59, 66–72 (2003).

7. McMillen, I. C., Kok, J. S. M., Adamson, M., Deayton, J. & Nowak, R. Development of Circadian Sleep-Wake Rhythms in Preterm and Full-Term Infants. Pediatr. Res. 29, 381–384 (1991).

8. Mindell, J. A., Telofski, L. S., Wiegand, B. & Kurtz, E. S. A nightly bedtime routine: impact on sleep in young children and maternal mood. Sleep 32, 599–606 (2009).

9. Illnerová, H., Buresová, M. & Presl, J. Melatonin rhythm in human milk. J. Clin. Endocrinol. Metab. 77, 838–841 (1993).

10. Cubero, J. et al. The circadian rhythm of tryptophan in breast milk affects the rhythms of 6-sulfatoxymelatonin and sleep in newborn. Neuro Endocrinol. Lett. 26, 657–661 (2005).

11. Cohen Engler, A., Hadash, A., Shehadeh, N. & Pillar, G. Breastfeeding may improve nocturnal sleep and reduce infantile colic: Potential role of breast milk melatonin. Eur. J. Pediatr. 171, 729–732 (2011).

12. Burnham, M. M., Goodlin-Jones, B. L., Gaylor, E. E. & Anders, T. F. Nighttime sleep-wake patterns and self-soothing from birth to one year of age: a longitudinal intervention study. J Child Psychol Psychiatry 43, 713–25 (2002).

13. Pinilla, T. & Birch, L. L. Help me make it through the night: behavioral entrainment of breast-fed infants’ sleep patterns. Pediatrics 91, 436–44 (1993).

14. Wolfson, A., Lacks, P. & Futterman, A. Effects of parent training on infant sleeping patterns, parents’ stress, and perceived parental competence. J Consult Clin Psychol 60, 41–8 (1992).

What This Study Shows

This was a cross-sectional study of children ages 1-6 in Toronto, Canada. Blood samples were taken from 1647 children, and their mothers were asked, “How long has your child been breastfed?” We always have to be cautious about studies based on parental recall. However, research shows that mothers actually answer this question with good accuracy (Li et al. 2005). Of the children in this study, 93% had been breastfed at all, and median breastfeeding duration was 10 months. Twenty-seven percent of children were breastfed for more than one year, and 4% breastfed for more than two years.

The children’s blood samples were analyzed for serum ferritin and hemoglobin. Serum ferritin reflects the amount of iron stores available for use by the body, so it can be used to assess iron deficiency. If an iron deficient child also had low hemoglobin, he was diagnosed as having iron deficiency anemia. In this study, the prevalence of iron deficiency was about 9%, and 1.5% had iron deficiency anemia, findings similar to other studies in developed countries (Baker et al. 2010, full text here).

This study showed that kids that were breastfed for longer were more likely to be iron-deficient. Each month of breastfeeding beyond baby’s first birthday increased the risk of iron deficiency by about 5%. Children who were breastfed for longer than a year were estimated to have 1.7 times the odds of being iron deficient than those breastfed for less than a year. The researchers corrected for several potentially confounding factors: age, gender, birth weight, BMI, ethnicity, household income, day-care attendance, age of introduction of solids and cow’s milk, and current daily intake of cow’s milk. Children with iron deficiency were also more likely to be heavier at birth (bigger babies have higher iron requirements), younger (meaning that older kids seemed to have recovered from iron deficiency), and to be drinking more cow’s milk (something I wrote about here). Breastfeeding duration was not associated with iron deficiency anemia, which would indicate a more severe deficiency.

An obvious limitation to this study was that the observed relationship between breastfeeding and iron deficiency was just a correlation. There are other factors that could come into play that weren’t examined, like timing of umbilical cord clamping and how much iron these kids were getting from their diets or supplements. For example, it’s possible that moms who breastfeed longer are less likely to give their toddlers a multivitamin or other iron supplement. It that case, it wouldn’t be the breastfeeding that increased the risk of iron deficiency, but rather something else about moms who choose to breastfeed beyond a year. This is a major limitation, but to be fair, almost every study that shows positive outcomes for breastfeeding has the same problem.

Why be concerned about iron deficiency?

Iron is a mineral essential to life in all animals. Most of the iron in the body is used to make hemoglobin and myoglobin, so iron is really critical for oxygen transport to all tissues of the body. Iron is also part of several enzymes involved in energy metabolism. Every cell in the body requires iron, but blood, brain, and muscle cells are the ones that really suffer if there isn’t enough iron around. A person with severe iron deficiency will develop iron deficiency anemia, one of several types of anemia.

Iron deficiency in the first years of life, even without anemia, has been associated with cognitive, motor, and behavioral deficits (Lozoff et al. 2006). There are a lot of confounding variables in these studies, because kids that are iron deficient are likely to have other disadvantages as well. However, there are mechanisms for a causal relationship established through animal research (McCann and Ames 2007). So there’s some controversy as to just how scared we should be about iron deficiency, but given that we’re talking about brain development of our kids and that iron deficiency can be corrected with dietary changes, I think we should pay attention to it.

The current study was the first to look at the relationship between breastfeeding and iron in toddlers. Many studies have shown that exclusively breastfed babies are at higher risk for iron deficiency during late infancy (reviewed by Baker et al. 2010, full text here). Human breast milk is low in iron, but babies are usually born with enough iron, passed from mom via the placenta, to last for about the first six months. Delayed cord clamping at birth can extend the iron stores by another month or two. If breastfed babies aren’t getting some good iron-rich solid foods by late infancy, they can become iron-deficient.

So should I be worried about my breastfed toddler?

Worried? I wouldn’t go that far. Instead, I’d say you should be alert to the possibility that your breastfed toddler could become iron deficient. The good news is that it isn’t that hard to prevent iron deficiency if you’re mindful about nutrition.

How can I ensure that my breastfeeding toddler is getting enough iron?

Why would a breastfed toddler be at greater risk for iron deficiency? The study at hand doesn’t tell us, but I’ll speculate for you. Breast milk doesn’t have much iron. Yes, the iron in breast milk is well-absorbed, but there is still very little there. That’s probably a good thing for an infant (more on that here), but it means that breast milk really can’t provide complete nutrition for a growing toddler. Toddlers need good iron-rich sources of solid foods in their diets.  If a toddler fills up on breast milk, then it may be challenging for him to get balanced nutrition.

So how can you make breast milk part of a balanced diet for a toddler?

• Talk with a health care provider about your child’s risk for iron deficiency. Consider having him tested so that you know if you should be concerned. If he does test low for iron, then depending on the severity, your pediatrician might recommend a supplement or suggest trying to correct the problem through diet.

• Include lots of iron-rich foods in your toddler’s diet, like meats, legumes, whole grains, green veggies, and dried fruits. Of course, toddlers can be picky, so this may be easier said than done. Know that it may take many low-pressure exposures for your kid to be ready to try new foods. Iron-fortified breakfast cereals are a good option for more skeptical eaters. You can find a list of iron-rich foods, as well as strategies for increasing iron absorption, in this post.

• Cow’s milk inhibits iron absorption. If your toddler is breastfeeding AND drinking cow’s milk, consider limiting cow’s milk to just one or two cups per day (or even none at all). Of course, without cow’s milk, you’re losing a good source of vitamin D (also low in breast milk), so you may want to consider a vitamin D supplement.

• Evaluate if breastfeeding is getting in the way of your toddler eating well at meals. This might be an issue if you’re breastfeeding on demand throughout the day. Toddlers do better with eating if they have structure around their meals and snacks. To you and your toddler, breast milk is probably much more than a food. It is comfort, closeness, and a moment of quiet together. But, it is also calories, and there’s no getting around that. Toddlers who snack on breast milk throughout the day might not come to the table hungry and be ready to eat a variety of foods with the rest of the family. If that seems like it might be an issue for your child, consider fitting breastfeeding into times of day when it is unlikely to interfere with eating, such as before nap and bedtime.

If you’re breastfeeding beyond a year, what do you do to balance breast milk and foods in your toddler’s diet?

I’m fascinated by cultural variation in nighttime parenting strategies. However, according to some accounts, there’s a simplistic dichotomy in the way parents around the world help their babies sleep. In most of the world, mothers sleep with their babies and breastfeed on demand throughout the night. Sleep is not a problem, because babies simply aren’t expected to sleep through the night. We in the West, however, don’t understand normal infant sleep. We bend over backwards with all sorts of tricks and gadgets to help our newborns sleep, often alone. (I’m looking at you, swings, bouncy seats, strollers, drives in the car, exercise balls, washing machines.) Then, a few months later, we tire of the antics, grow intolerant of night wakings, and turn to sleep training as the answer.

There is definitely some truth to this. It’s something that I’m writing about in greater detail in my book. But we also know that nothing is as simple as it seems, and infant sleep is no exception. I think it’s helpful to know that parents everywhere struggle with their babies’ sleep or lack thereof, and that’s true regardless of sleep customs or cultural expectations (Sadeh et al. 2011). No matter where they’re born, babies have to acclimate to a world that grows dark and quiet at night and bright and busy during the day. We might use different strategies to help our babies sleep, but there are many similarities as well.

I ran across one of these similarities in a paper I read yesterday (Anuntaseree et al. 2008). Thai researchers surveyed parents of three-month-olds born across the country in 2000. They asked the parents how their babies fell asleep, where they slept, how they were fed, and how often they woke during the night. The parents of more than 3700 babies responded to the survey.

Most of these babies – 68% – shared a bed with their parents. The rest slept in a separate bed but in the same room. Putting babies to sleep in a separate room was nearly unheard of. Of 3700 babies, only two slept alone (a whopping 0.05%). About half were exclusively breastfed, and another quarter were fed a combination of breast milk and formula. On average, these three-month-old babies woke their parents 2.7 times per night, but there was of course a lot of variation here. Nearly 50% woke just one or two times per night. The researchers wondered which factors were related to waking more often, and they found significant correlations with these: male gender, more than three naps per day, falling asleep while feeding, exclusive breastfeeding, and the use of a swinging or rocking cradle.

The gender and napping associations are a little odd and not supported by other studies. However, the rest of it isn’t surprising. It is well accepted that breastfed infants wake more often during the night. Human breast milk is more rapidly digestible than formula (Cavell 1981), so breastfed babies need to feed more frequently. It’s also a common finding that feeding to sleep increases waking (or more accurately, waking the mother) during the night.

But I was really interested in learning more about the swinging or rocking cradles mentioned in this paper. It turned out that 88% of babies commonly started their night in such a cradle. Here’s how the paper described it:

“Use of a swinging or rocking cradle for infant sleep is traditionally used in many Asian countries including Thailand. The typical “getting the infant to sleep” situation in Thailand is for parents to use a cradle as a sleeping aid, and then when the infant falls [to] sleep, transfer the infant to the bed. There has been no previous study regarding the effect of this custom on night waking; our study is the first to demonstrate this association.”

Photos by Jop Timmers

I was curious about what a Thai swinging cradle might look like, so of course, I Googled it. The only photos I found showed a pretty extraordinary contraption:

I found these photos on this design blog and emailed the author, Jop Timmers, to see if I could repost his photos here. He happily agreed, and he told me a bit more about the photos:

“The picture was taken in Kong Chiam, close to the Mekong River and near the border with Laos. The grandmother was trying to make the crying baby of 9 months old to become quiet and go to sleep. The speed was dazzling, but it worked, the boy fell asleep almost instantly. It was a habit of her to do so.”

Anuntaseree et al. consistently refer to “swinging or rocking cradles,” so I assume that the swinging design is not unusual. I’m picturing the rocking cradles as being more similar to the traditional European design, but that’s just a guess. Anyone have more knowledge of these cradles?

There are a few things to point out about this Thai study. For one thing, rocking or feeding to sleep didn’t doom parents to sleepless nights. Plenty of babies in this study fell asleep this way and only woke once or twice. And second, this Thai study just identified associations. (As I said, it isn’t particularly groundbreaking work, but I think it is interesting from a cross-cultural perspective.) As with any cross-sectional study, we don’t know for sure if it is the infant influencing the parenting practices or vise versa. It is surely a bit of both. But several lines of evidence support the idea that parental practices shape baby’s sleep. One study found that mothers’ ideas about infant sleep during pregnancy predicted how many times their babies would wake during the night at 6 months, and this effect was mediated by the way they soothed their babies (Tikotsky and Sadeh 2009). And when parents are counseled, even prenatally, on early strategies to encourage their babies to learn to go to sleep on their own, their babies end up with fewer night wakings (Pinilla and Birch 1993, Kerr et al. 1996, Wolfson et al. 1992). In other words, how you parent around bedtime and during the night has at least some impact on how your baby sleeps.

The strategy of using motion to help babies fall asleep must be universal. We parents find that if we can mimic the motion of the uterine environment in some way, it is often soothing to our newborns. In the first weeks and months of parenting, we’ll do anything to help calm our babies. And really, who can blame us? But, at some point, we often find ourselves stuck with unsustainable sleep associations. Perhaps Thai parents are no different. The baby in the photos above has learned to fall asleep with motion akin to a carnival ride. This kind of environment is actually quite different from the one he experienced during fetal life, and at some point, he’s going to have to learn to fall asleep while his body is still.

I have a love-hate relationship with motion as a sleep aid. We bounced Cee to sleep on an exercise ball for most the first three months of her life, and this may have saved my sanity and feelings of self-efficacy as a new parent. But then I was horrified when I realized that she couldn’t wind down without a fairly vigorous 30 minutes or more of bopping up and down. For her, learning to fall asleep without motion made all the difference in the quantity and quality of her sleep. I wish that I had supported Cee in learning to fall asleep in stillness or even a more gentle, sustainable motion, a bit sooner. Of course, that’s always easier to say in hindsight. At the time, we were surviving one day at a time.

I don’t think we should be afraid to rock our babies to sleep for as long as we want. We should just know that it might be causing baby to wake more later in the night. If that doesn’t appeal to you, consider helping your baby to learn some other ways to fall asleep. If a baby falls asleep in conditions that are similar to those he’ll feel when he wakes briefly during the night, he’s more likely to be able to yawn and go back to sleep. The key is to find opportunities to make that a gentle transition earlier in life, lest you end up with a nine-month-old who requires “dazzling speed” to get some rest.

Did you use motion to help your baby sleep? How did you transition away from that strategy?

While we’re talking baby cradles from around the world, here’s a few more cool cradles that turned up in my Internet meandering. And if you can’t tell, I’m really having a lot of fun with this research!

This one is labeled as a “Primitive African handcrafted baby cradle” and is for sale on 1stdibs.com.

A gorgeous Japanese cradle, dated 1701-1850, inlaid with tortoise and abalone shells. I wonder if that hole in the bottom third has something to do with diapering or lack thereof?

Photo from Science Museum, London

An Italian cradle, dated 1600-1750, made of fabric covered in plaster.

Photo from Science Museum, London

And finally, here’s a modern cradle with a cool design. Of course, you might prefer to just hold your baby if you’re going to rock him to sleep, but this cradle does eliminate the delicate transfer maneuver (although this doesn’t look like a safe place for a baby to sleep unsupervised for the night).

WHAT THE WORLD LOOKS AND SOUNDS LIKE TO A NEWBORN BABY

By Susan Brink

Imagine yourself in Paris, and you don’t speak French. Pretend for a moment that you’re from rural America, have never seen a big city much less the elegant capitol of France, and you’re trying to cross the Champs-Elysees at the Arc de Triomphe. You dare not step into traffic, you can’t read the street signs, and you cannot understand what people are trying to tell you. Sights and sounds overwhelm you. Nothing makes sense.

That’s something to think about when wondering what the world looks and sounds like to a newborn baby. But there’s more. Dr. Alison Gopnik, professor of psychology at the University of California, Berekley, adds two elements to the confusing mix: love and caffeine. “You want to know what it’s like to be a baby?” says Gopnik. “It’s like being in love for the first time in Paris after four double espressos. It’s fantastic. It’s a wonderful state to be in. And very likely, you’ll wake up at three a.m….crying.”

We look into a newborn baby’s eyes and wonder what he sees. We watch her reactions and wonder what she hears. But now we’ve got a wealth of recent research into what newborns see and hear that adds scientific chops to what parents have been imagining for ages.

Vision

After counting fingers and toes, the first thing most parents do is gaze into their infants’ eyes. We tell ourselves that they’re looking right back. But what, exactly, do they see?

We know that vision is the least developed sense at birth. Babies have heard their mothers’ voices through layers of flesh and organ for nine months already, and they recognize her voice at birth. But they have no similar recognition of her face. Already, they can discern contrast and are drawn to the shadows of eye sockets and the edges of faces. But vision has multiple components, including focus, contrast, coordination between eyes, depth, distance, and color. Their developing brains must lay down dendrites and create synapses between cells in visual areas of the brain, the networks that send and receive signals.

Even as that important brainwork is going on, parts of the eye itself must physically develop. At birth, an infant can project a clear image onto the retina, the light-sensitive tissue at the back of the eye. The images are converted to electric signals and sent on to the brain to interpret. But the fovea, the part of the retina that gives good, detailed vision, is not yet mature. The muscles controlling coordination of binocular vision aren’t yet strong. And the brain architecture that will eventually interpret the signals is not yet up and running. So when a newborn baby looks at an object, the clear image received by the retina falls on a fovea too immature to transmit a clear image to visual areas of the brain. And those visual areas are themselves just beginning to form. In time, the fovea will mature and pass on clear images. And with every visual sensation, the brain adds structure to enable more complete vision.

With every open-eyed observation that passes their way, information is making its way from the eye to the developing visual centers of the brain.

In other words, vision develops through the inevitable practice of looking around.

What Infants See Right Away

Almost from birth, infants are drawn to contrast. We tell ourselves that the baby is looking right into our eyes. If she is, it’s because she notices the contrasting shadow of the eye socket. But it’s equally likely she’s looking at the edge of our face because she’s drawn to the contrast of head against background. For example, newborns can see measurable contrast between very light and very dark objects. At a distance of one foot, they can see high contrast black lines on a white board—lines only 1/16” wide. They notice movement of large, high-contrast objects. In another month, they’ll see some reds and greens. By two months, they’ll be drawn to all the details a loving face, not just the edges and shadows; and they’ll begin to respond to more subtle motions, like the movement of a hand in front of their faces.

There is important visual work going on in the months before a baby actually sees. If the visual pathways, ripe for development early in life, are completely blocked during crucial early periods, the result will be permanent visual impairment. But relax. A healthy baby living within anything resembling a normal human environment will not have those critical pathways blocked.

Research using animal models in the 1960s showed why early visual experience is so important. In experiments done with newborn kittens, scientists sewed shut one eye of each kitten and left it that way for several weeks. When the sutures were removed and the eye allowed to open, the kitten still could not see from that eye, even though the eye was perfectly healthy. What the experiment showed was that if the eye and brain fail to make connections during crucial periods of development, the visual cortex undergoes dramatic reorganization and vision never develops normally.

David Hubel and Torsten Wiesel, Nobel Prize–winning scientists who pioneered this vision work, repeated their work with monkeys. They found that in the normal monkey brain, there are columns of neurons in the visual cortex. Each column receives input from one eye, and the columns alternate between those dominated by information sent from the left eye and those dominated by information from the right eye. The alternating columns allow the brain to start putting that information together as binocular vision.

But among the monkeys deprived of vision in one eye, the neural columns dominated by the seeing eye became wider. The neural columns associated with the blinded eye became narrower. It became clear that in order for monkeys or kittens to see normally, they had to have visual experiences during the earliest weeks of their lives. Without it, the brain’s capacity to make the necessary neural connections was gone.

But the world provides exactly the right visual stimulation for healthy infants without the need of special toys or mobiles. We all have blue sky above, and green trees below and the view of the firmament through branches is a glorious feast of vision. And quite simply, there is nothing an infant likes better than a close-up view of a parent’s face.

It’s a difficult and imprecise business, knowing what a baby is seeing or recognizing. But parents and babies have always gazed into one another’s eyes. It’s deeply rooted, it’s bonding, it’s complex—and it’s important.

Sound

A fire truck screaming, a vacuum cleaner roaring, a talk show host droning, grown-ups chattering, children nattering, dishes clattering. For a newborn baby, the sounds are all there, but the brain isn’t ready to assign more or less importance to any one of them. As a fetus, he heard most of it before, but in utero the sounds were mercifully muffled, almost soothing. The most soothing of all sounds in the new world no doubt is also the most familiar—mother’s voice. Newborns recognize their mothers’ voices, turning toward them more readily than toward any other voices.

Hearing is the most highly developed sense at birth—but newborns cannot yet discern what is worth listening to and what can be safely ignored. They don’t yet have the skill to know where a dog bark ends and a screaming sibling begins, much less to know where one word ends and another begins.

But during the first three months of life, they set about the work, bit by bit, of organizing the sounds around them.

Sorting Through the Din

Think of newborn hearing as a passive exposure with the baby’s brain soaking up sounds and being bathed in the acoustics of his surroundings. Just as each little peek of vision is sculpting new brain circuitry to enable sight, each phrase and sentence sets up the brain wiring that will soon allow the baby to understand where one word ends and another begins. Long before she utters her first “ma-ma” or “da-da,” she’s building the foundation for speech and understanding language.

Babies begin to learn language by listening. And they need to hear human voices. Television and video doesn’t work. That’s because part of what’s needed to learn is human interaction. They learn early on that even their accidental sounds—a burp, a sneeze, a hiccup—get a reaction: a back pat, a gesundheit, a startled look. Soon, another kind of accident happens. The baby leans his head back, the tongue hits the roof of the mouth, and a “g” or “k” sound emerges as he exhales an “oo” sound. It’s a coo! And research tells us that when parents coo back, infants respond by babbling more.

All babies around the world are born with the ability to recognize every sound made in every language on earth. But within months, we lose that ability. The brain is an efficient organ, and just as it’s busy building the connections it will need, it also works at pruning away those neurons that will not be needed.

Dr. Patricia Kuhl, a neuroscientist and professor of speech and hearing at the University of Washington and a leading expert on speech development, discovered why it is that Japanese people have difficulty mastering the ra and la syllables of the English language. Dr. Kuhl and her colleagues tested infants using special pacifiers connected to computers. The infants loved new sounds, and sucked up to eighty times a minute to keep the sound going. But infants, like all of us, get bored with repetition. They eventually slowed down after hearing the same sound over and over. Then as a new sound was introduced, they again sped up their sucking.

Using these special pacifiers, researchers found that infants as young as one month of age heard all sound distinctions— the ones that would become part of their native language, as well as others that they were unlikely to hear as adults. The Japanese babies in the study could tell there was a change in sound when they heard rake and then lake. Japanese adults cannot make the distinction—even the Japanese scientists involved in the experiment couldn’t do it.

When tested at ten months of age, the Japanese babies could no longer make the distinction. If they heard the ra sound long enough to get bored, and then the sound changed to la, they remained bored and inattentive. Whatever inborn ability they had to make the distinction was lost to brains that were preparing themselves for the sounds that would be needed in Japan.

And so it is around the world. A French baby and an American baby have the same ability, for several months, to hear the guttural, rolling r of the French language. Within ten months, the American baby has lost it, and if she tries to learn the French language as a teen or an adult, the unnatural attempt to say rouge or après can be challenging, if not downright embarrassing.

Babies love the sound of voices, the lilt of language. They want it to be interactive. They want to connect facial expressions to words, and every word you utter—for this brief period of time—will be completely fascinating to this listener.

It seems that, once again, nature and biology know what they’re doing in giving sound a head start on vision The world is a confusing enough place to enter with good hearing. It’s probably best that infants are more able to begin understanding sounds as their brains quietly go about the business of developing vision.

Susan Brink is a freelance medical writer. Her book, “The Fourth Trimester: Understanding, Nurturing, and Protecting an Infant Through the First Three Months,” is published by the University of California Press and was released March 20, 2013.

What is a blog carnival? It’s a collection of blog posts, all focused on one theme, submitted by various bloggers. We plan to hold our carnival every month or two, rotating hosts to different blogs and choosing a new theme for each carnival. Bora Zivkovic of A Blog Around The Clock wrote about blog carnivals in his post on the history of science blogs. Carnivals aren’t as common now as they once were. Instead, bloggers are sharing their work through social media outlets. But as Bora wrote, carnivals do something that social media can’t: “Each edition of a carnival is a magazine, a snapshot of the moment, and a repository of pieces that both their authors (by submitting) and hosts (by accepting) thought were good and important.” This is what we’re hoping to capture in our collections of posts on parenting and science.

Since I have the honor of being the first host of this Carnival, I’ve been thinking about what “Evidence-Based Parenting” means to me.

If you had asked me what evidence-based parenting meant when I first became a mom, I probably would have said something along the lines of, “doing everything right.” Now I know better.

I know that parenting is complex. I know that there are countless factors that enter into our parenting decisions, and even the best science can’t describe all of those variables. I’m a scientist by training, and I like to see data when I’m faced with a tough decision. But if I’m wondering if preschool is right for my kid, then I know that looking at the data will give me some ideas about important considerations and average outcomes, but it still isn’t going to tell what is the right choice for my child.

Why, then, do we care about the science? There’s something about parenting that invites judgment and controversy. Maybe it’s because we care so much about getting it right, but deep down, we’re afraid we’re doing everything wrong. Pick a parenting controversy, do an online search, and you’ll find strong voices supporting opposing sides. They’ll also both be citing science to back their opinions. My only solution to cutting through the spin in these cases is to get to know the field and broadly understand the evidence base for it. Or perhaps better still, since we’re busy parents and all, find someone you trust who can do this for you. That’s what this carnival is all about: science-minded bloggers compiling some of our best resources on a given topic to bring you a summary of the important science. It’s helpful (and more fun!) to work together on this, because we know that a true base of evidence requires multiple viewpoints, all committed to looking through the lens of science.

Evidence-based parenting means recognizing what we don’t know as well as what we do. It is an attempt to understand the questions as well as the answers. It isn’t a search for the One Right Way so much as it is a quest to understand the variation, complexity, and bias inherent to real life. After all, no scientist will tell you that their research has answered all the questions; instead, they know that every new experiment uncovers both new knowledge and new questions. To me, it is this spirit of curiosity that defines evidence-based parenting.

Let’s get to the posts for our first Carnival. Preschool: Do you need it? What kind is best? How can we even measure that?

Melinda Wenner Moyer’s piece on Slate, The Early Education Racket, stimulated a lot of conversation in my parenting circle. “Research suggests that if you have the time and money to argue over the merits of a Waldorf preschool versus a Montessori one, little Emma isn’t going to suffer either way. In fact, she probably doesn’t need to go to preschool at all,” Moyer writes. Start your Carnival reading here and breathe a sigh of relief. Your kid will probably be OK, whatever choices you make for preschool.

I know you’re still curious, though, so keep reading.

Over at Momma Data, Polly Palumbo lays out the evidence for why play is so important for preschoolers. Children learn naturally through play, and research shows that direct instruction like that found in academically focused preschools might actually get in the way of children’s curiosity, creativity, and natural development of problem-solving skills.

Jessica Smock of School of Smock writes about families that are opting out of formal preschool altogether and instead choosing to home school their preschoolers. Jessica explores some of the reasons behind this choice and what exactly a home-based preschool “curriculum” looks like. There are companies out there that will happily sell you a curriculum package with promises of giving your kid a jump-start in math and reading, but Jessica cautions against this approach. What preschoolers really need is – you guessed it – play! That’s true whether your child is learning at home or in a classroom.

Here on Science of Mom, I tackled another question that might play into your choice of preschool: Which is a better preschool environment, mixed-age or single-age classrooms? I wanted to learn more about this question because Cee is currently in a mixed-age, at-home daycare (not technically a preschool, but close enough for me). I found lots of interesting studies on the effects of age composition on children’s learning, but I also had fun critiquing those studies.

In her post, Momma, PhD gives her own account of the factors that went into choosing a preschool for her daughter. As a working scientist herself, Momma, PhD knows that kids are natural scientists, and the way they experiment is through play. That was a major factor in their preschool decision. She and her husband ended up choosing a modified Montessori program, so you’ll definitely want to read this post if you’re interested in this teaching philosophy.

Speaking of scientists, Jeanne Garbarino, Biology Editor at Double X Science, submitted a piece she wrote for Agora. Jeanne writes about her daughter’s natural curiosity about science and ponders how to answer her questions. She comes back to recent research about how kids learn best. It isn’t through direct instruction, even when your mom knows the answers. It’s about letting kids discover answers on their own and acknowledging that the process is just as important.

Jennifer Doverspike of Six Forty Nine sorted through a tremendous amount of research in search of answers to an important question: How do we define quality in preschool? And in a word, it’s complicated. And difficult. (OK, two words.) That’s actually not a big deal to many of us, because chances are good that we’re choosing between several high quality preschools. But it matters a lot to families who don’t have much choice, like those sending their kids to local Head Start programs. How do we give those kids the best preschool experience possible, and do it on a mass scale? These questions are really important to education policy. (This post is actually Jennifer’s third in her series on preschool. She’s also written recently about if preschool is necessary and if Head Start works.)

Suzanne Barston of Fearless Formula Feeder wondered if she should be concerned about the teaching style at her kids’ “down-home” preschool, but she quickly learned that the research is confusing and hard to interpret if you’re looking for answers to your personal preschool questions. “But through the panic, the uber-rational devil on my shoulder kept whispering “does it really matter? It’s preschool.” Sometimes recognizing the limitations of the science provides just enough reassurance to trust your gut, and that’s a good thing.

Finally, Tara Haelle at Red Wine and Apple Sauce walks us through a recently published study on the success of one preschool program. It’s helpful to look closely at one study in this way, because then you can start to see the limitations inherent to any single study. That’s something that you might not learn from media accounts of hot new research. Real outcomes from preschool are hard to study, so it takes a lot of work to understand what is effective and what isn’t. Like all of science, it isn’t a single study but rather a body of evidence that matters.

I loved reading all of these posts, and I encourage you to click through and check them out. Even though we tackled different questions, there was a clear theme that emerged. We all recognized the importance of play and discovery in preschool, and we were cautious about pushing kids to an academic curriculum too soon. That’s interesting coming from a group of highly educated women. I can’t help thinking, if Cee is going to follow in the footsteps of her parents, she may have a few decades of school ahead of her. Why not play a little longer?

We’d love to hear your comments – here or on our individual posts. How did you choose preschool – or not – for your children? How much was science and how much was gut?

You can also follow our discussion on Twitter with the hashtag #parentscience.

A quick list of our contributors for this First Edition of the Carnival of Evidence-Based Parenting:

The Early Education Racket (Melinda Wenner Moyer)

Preschool Should Be Less School and More Play? (Momma Data)

Preschool at Home? Let the Children Play! (School of Smock)

Mixed-Age Preschool: Benefits and Challenges (Science of Mom)

Picking a Preschool (Momma, PhD)

On parenting (and teaching) in the name of science (Jeanne Garbarino)

Universal Prekindergarten: Evidence from the Field (Six Forty Nine)

Preschool Schmeeschool (Fearless Formula Feeder)

What Can We Learn from a Single Preschool Study? (Red Wine and Apple Sauce)

One of the reasons why we chose Amanda’s for childcare is that it allows Cee to interact with kids of different ages. When I first visited Amanda’s, the problem-solving and conflict resolution that I observed among the older kids impressed me. It was refreshing to watch, particularly after visiting chaotic childcare centers with rooms of as many as 10 two-year-olds. I imagined that Cee would learn so much from observing and playing with these more mature children.

When Cee began daycare last fall, we watched as two older girls took her under their wing, reading her stories and including her in their pretend play. Suddenly Cee was acting out complex stories at home, too, as she became aware that her imagination could make all kinds of fun. She was making us coffee, asking if we wanted it hot or cold, with milk or sugar. She was hushing us because her baby doll was sleeping. And she could not stop talking about her friend, the kindergartener, who rode on a real, honest-to-goodness school bus. We also watched, proudly, when she stuck up for herself and brushed off older kids if their play was too intense for her. She seemed to make a huge developmental leap within a couple of weeks of starting childcare.

Delivering Valentines to her friends

I’ve also noticed that the friend that Cee talks about the most at home, and the one that she hugs the longest when she says goodbye, is a little girl just 2 weeks younger than her. I’ve witnessed them engaged in complex, interactive play together, where neither is the obvious leader or follower. And while I think Cee is doing great in her mixed-age childcare setting, I wonder if I’ll feel differently about this as she gets older. We could keep her at Amanda’s through kindergarten, but when she’s four or five, will hanging out with toddlers be a bore? Should we consider moving Cee to a preschool where she’ll be surrounded by kids her own age? Is mixed-age grouping helpful for preschoolers, or does it slow them down?

Child development experts have debated the merits of mixed- vs. single-age classrooms since the 1930s. Soviet psychologist Lev Vygotsky was an early proponent of mixed-age learning. He thought that the best way for children to learn was through interaction with older, more competent children who could set good examples for cognition and behavior. According to Vygotsky, hanging out with older children pushes younger ones to learn more than they would be capable of learning on their own. In contrast, Jean Piaget, well-known for his theory of cognitive development, believed that children learn best from peers close in age, well-matched in knowledge, skills, and power. With their peers, children can learn to solve problems organically and to practice playing a variety of roles in solving them, rather than always being guided in how to fix things by an older, more experienced child.

Decades of research haven’t been able to clarify whether mixed-age or single-age classrooms make for better preschool environments. Some studies point to benefits of mixed-age grouping, similar to my own observations. Toddlers who have a chance to play with slightly older kids seem to develop more complex language and types of play (Rothstein-Fisch and Howes 1988; Howes and Farver 1987). And in mixed-age classes, older children have opportunities to practice leadership skills and prosocial behaviors, like helping and sharing (Derscheid 1997; French et al. 1986).

Mixed-age classrooms might also have the benefit of muddying age-based comparisons and competition between children – a good thing, I think –  because there is likely to be a naturally wide range of skills and abilities within the class. As a parent, it is hard to fret that your child is behind the curve if there is no real curve. And teachers might be more likely to work with children where they are, focusing on their individual interests and skills rather than expecting the entire class to move linearly through milestones and achievements. Plus, mixed-age classes make it logistically easier to keep the same teacher with a group of kids for several years, maybe decreasing the stress of abrupt classroom and teacher changes for young kids (Whaley and Kaplan 1992).

However, there is also a fair amount of research pointing to problems with mixed-ages, the main concern being that mixed-age classrooms don’t challenge older children enough. For example, one study found that older children in a mixed-age setting were more likely to be hanging out solo, detaching themselves from the rest of the group, than if they were in a class of closer peers (Urberg and Kaplan 1986). Another found that older children were less likely to take part in teacher-led activities in mixed-age groups, probably because it is challenging for teachers to plan activities that are appropriate for a broad range in ages (Goldman 1981).

We’re starting to see a pattern emerging here, right? Mixed-age classrooms seem to generally work well for the younger kids in the group, but the older kids might be missing out. A 2002 study headed by Adam Winsler of George Mason University illustrated exactly this pattern in a university-affiliated child development center with morning-only care and a child-centered, play-based philosophy. This study was unique in that it took advantage of the center’s switch from single-age to combined 3- and 4-year-old classrooms, tracking children’s behavioral and cognitive development during the years before and after the switch. Research assistants carefully observed the minute-to-minute activities of the children. Were they engaged in a focused, goal-directed activity? How long was their attention focused on that activity? Were they working alone, with another child (close or distant in age), or with a teacher? A limitation of this design (and most studies like it) is that it can’t be blinded, so it’s possible that the researchers were just seeing what they wanted to see. However, that specific checklist of observations decreases the chances of this being a problem.

How did the children’s behavior differ between single-age and mixed-age classrooms in Winsler’s study? When kids were in single-age classrooms, the 4-year-olds were more “on-task” and had longer attention spans for a given activity. They also spent more time with their peers and less time with their teachers compared to the 3-year-olds. But when those two age groups were combined into one room, the age differences essentially disappeared. The 3-year-olds started acting more like 4-year-olds, and the 4-year-olds started acting more like 3-year-olds. For example, in single-age classes, the 3- and 4-year-olds were working on goal-directed activities 63% and 85% of the time, respectively. When they were thrown into a room together, those numbers shifted to 71% for the 3-year-olds and 70% for the 4-year-olds.

Reading this study got me thinking about the challenges of figuring out what exactly to measure if we’re trying to quantify effectiveness of a preschool program. This isn’t my field at all, so these study methods were new to me. (And, to be fair, the Winsler study is more than a decade old, and the research methods of the field have no doubt changed since then.)

For example, what exactly does it mean for a 3-year-old to be “goal-directed”? Here’s how the Winsler paper described it:

“Goal-directed activity was defined as behavior by the child, which appeared focused, organized, and had an identifiable goal or end point to the activity… Examples of goal-directed activity… included building a structure out of Legos or some other assembly/construction materials, doing a puzzle, playing a game with rules, or engaging in an organized make-believe episode of ‘house.’ Nonexplicitly goal-directed behavior in this context included, for example, aimless wandering around the classroom, looking on into another group’s activity, repeatedly spinning a puzzle piece around one’s finger for the apparent ‘fun of it,’ and making a transition between one activity and another.”

I get that we like to see kids focused on a project or game. Learning is more obvious in this context. But I wouldn’t disregard daydreaming as unproductive activity; science is revealing that daydreaming is actually an indicator of a busy and active brain. And who’s to say that a child isn’t learning a great deal from observing other kids? Or that repeatedly spinning a puzzle piece around one’s finger isn’t the beginning of a passion for physics? Maybe being an older kid in a mixed-age group means spending less time on “school-readiness” activities and more time playing alone and developing empathy and leadership, but how much does each of these contribute to how your kid will ultimately get along in the world? How much do we really know about how kids should and shouldn’t be spending their time?

To their credit, Winsler et al. make this exact point:

“The finding that 3-year-old children in MA [mixed-age] groupings are stretched a bit behaviorally while this is not the case for the 4-year-olds would appear to give some support to the fears reported by parents who typically prefer their child to be the younger child in MA settings (Lloyd, 1999). However, it is important to point out that these data (nor the data from any other studies for that matter) do not imply that MA classrooms are bad for the older children in such classrooms. First of all, it is not clear that the outcome variables in the present study on which the age-by-age-composition interaction effects were observed (sustained activity, goal-directed activity, time spent with peers and a teacher) are predictive of child competence and later positive outcomes. Secondly, there could easily be other advantages to MA grouping for the older children (like the diversity of social experience afforded by increased gender and age desegregation or other social climate variables not explored in the present study) that balance or outweigh these findings.”

In other words, it is difficult for science to capture all the factors that might impact your child’s experience in preschool. Of the factors that we can capture, we’re not even sure how important they really are. Labeling one type of classroom as “better” and another as “worse” is bound to be a gross oversimplification. What the research does show is that the age composition of a classroom impacts how children spend their time, for better or for worse.

This research, with all its limitations, can be useful for informing education policy. For example, more 3-year-olds are now entering Head Start programs. Should Head Start classrooms mix 3- and 4-year-olds together, or should they keep them separate? If they’re mixed, then the research in this field can help highlight important aspects of teacher training, such as strategies for ensuring that children of all ages and abilities are engaged and challenged in their work. A couple of recent studies have looked specifically at the Head Start question, and again, found mixed results (Moller et al. 2008; Bell et al. 2013). There’s a lot more to learn about age composition in preschool classrooms.

Clearly “goal-directed”: Collecting eggs at Amanda’s

I don’t know whether we’ll move Cee to a more traditional preschool before kindergarten. But I like knowing about this research, because it will keep me thinking as I watch her grow up among her dear friends. I’ll be watching to see if she seems bored or disengaged from the group. But there are other factors that will play into our decision, like the stress of moving to a new school and her attachment to Amanda. For Cee, my priorities are that she be in a place where she is happy and feels safe, has lots of opportunities to play solo or with other kids, and that she grows her confidence in social situations. And to be honest, I’m glad she’s in a place where daydreaming isn’t discouraged.

A relatively relaxed moment in a calm, protected bay. She didn’t get much closer than this to the water’s edge.

We just got back from a week in Hawaii. It was a great trip and may become a February tradition now that we’re residents of the great and rainy state of Oregon. It was brilliant to escape the lingering wet winter, soak up a little sunshine, and relax together with some of our best friends.

We stayed just a couple of blocks from the beach and went there daily. I had pictured Cee playing in the sand and splashing in the waves. But the minute we stepped foot on the beach, Cee clung to my neck and did not want to be set down. It was yet another lesson in setting aside expectations and meeting my child where she was. And at this point in her life, she isn’t a fan of the beach.

Cee hasn’t spent much time at the beach in her short life, but this wasn’t her first time either. We visited Hawaii when she was 6 months old, and we’ve taken day trips to the Oregon coast a couple of times per year. But all of her previous experiences have been to rather wild coastlines, so she’s only dipped her toes in from the safety of our arms. I admit that we probably didn’t give her much choice about those early encounters. This was really the first time that she’s been able to verbally describe to us how the ocean makes her feel.

“I no like ocean.”

“Feel scared beach.”

“Go home, Mama?”

She’s terrified of the ocean.

And I can’t blame her. The ocean is huge. It’s unpredictable, powerful, and loud. It’s incomprehensible. To a two-year-old who wants to control her environment as much as possible, the ocean is frightening.

I tell her: It’s OK. I’m scared of the ocean, too. It’s OK to feel scared.

But let’s just put our toes in, I tell her. Let’s see how the water and the sand feel on our feet. She nods, though skeptically. I pick her up and we walk towards the surf. A wave approaches and breaks several feet out, and an inch or two of water and foam gently wash over my feet. She grabs me tighter and says directly into my ear, “All done, Mama! All done, Mama! All done, Mama!”

I respect that. I respect a little girl who can look me in the eye, head held high, and tell me she’s afraid. She says this even as children play around us, racing the waves breaking on the shore. I know that I can’t explain away Cee’s fear of something this big.

But I do want to tell her this:

The ocean terrifies me too.

But isn’t it beautiful? I think you’ll see this someday. And when you accept that the ocean is wild and huge, and there’s nothing you can do about that, you might find that it’s calming to watch the waves crash onto the shore from a safe spot further up the beach.

And maybe not today or this week or next year, but someday, you may want to step into this water despite your healthy fear of it. Someday you might want to know just how refreshing it feels to dive into the ocean. You might want to see the wonders of a coral reef through a snorkel mask. You might let go of your current need to control your surroundings and let this wild water push you around a little bit. You might even learn to harness it on a surfboard.

I know that you are a brave girl, whatever you think of the ocean. I’ve watched you climb to precarious perches on our furniture, in trees, and on the playground, but you are careful and calculating as you climb. You are in control of every single move. The ocean is too unpredictable. It doesn’t give you that control, and you can’t calculate the risks.

You may be more of a mountain girl than an ocean girl.

I know, because I am just like you, little girl. I’m afraid of the ocean, too. But I don’t want to let that stop me from experiencing the world.

(Also, there’s this: We have one of those Sleep Sheep that we turn on for white noise at bedtime. It has 4 options for sounds: ocean, rain, babbling brook, and creepy whale/alien songs. We’ve used the ocean option since Cee was a newborn, because I think it is the most calming of the 4. We brought sheepie with us to Hawaii, and on our trip and ever since, Cee has specifically requested the “up-high button” – the top one – at bedtime. That’s the babbling brook. No more ocean.)

Photo Credit: Lori Cole

I’m working on the sleep chapters of my book right now. I had originally planned one sleep chapter, but I’m realizing that it’s such a huge topic that it needs to be split into two chapters: one on the question of where baby should sleep and one on sleep strategies and sleep training.

I have been focusing on the question of bedsharing for the last several weeks. I have read the major studies associating bedsharing with SIDS and suffocation and studied the professional opinions of those recommending against bedsharing from a public health perspective. I have also read the studies coming from James McKenna, Helen Ball, and others that take a more holistic view of bedsharing. These authors talk about bedsharing as the cultural and physiological norm for human infants, particularly in the context of breastfeeding. They advocate for a more tempered view of bedsharing safety, one that recognizes that all bedsharing situations are not alike and that, though not proven, it is certainly possible that a safe bedsharing environment can exist.

I’m trying to understand both the science and the controversy of this topic. There are the data, and there are the people analyzing it and interpreting it. Reading these papers, I get the feeling that it is difficult to find someone conducting research in this field who isn’t at least a little invested in the outcome. I wonder if these guys ever sit in the same room together and talk it out, because it feels like they are coming from different planets. There’s the epidemiology planet, where numbers rule and nuance is scorned. (And don’t get me wrong – I’m a numbers girl – but I can see the limitations in them here.) Then there’s the anthropology planet, a beautiful land of skin-to-skin, breast milk, and perfect physiological attunement between mother and babe. In my opinion, neither world completely represents the reality facing new parents in today’s world.

I wonder, for example, if the members of the AAP committee, which recommends against bedsharing, have ever cared for a baby who had extreme difficulty sleeping alone. And I wonder if the anthropologists have ever cared for a baby who wanted her own space, perhaps needing a break from all that day-and-night sensory input. I have met both types of babies, and as parents, I think we have to recognize that their needs are not the same.

In the real world, lots of factors determine how different families handle sleep. Infant temperament is one of them. Safety is another. There are also cultural expectations, family dynamics, work schedules, parenting styles, and feeding methods to factor in. Where baby sleeps is a complex parenting decision, one that is exceedingly difficult to study in a quantitative manner.

As I’m writing this chapter, I’m trying to present the science in a balanced way. I also recognize that this parenting decision – and most of them for that matter – can never be reduced to science and statistics. Parenting is about people and their stories. I know that I need to understand those stories as well as the science to write a worthwhile book.

So, I’m hoping you can help me.

Help me understand WHY your babies slept where they did – in your bed or in a crib or some combination of the two. What factors were important in your decision? Did your baby sleep where you had planned, or did you have to adjust your expectations? What worked well about your arrangement, and what didn’t?

I may be interested in including some of your stories in my book, but I’ll send you a direct email if that’s the case. Thank you – as always – for sharing your stories!

Here’s an important question that I’m struggling with, and I’d like your advice. How do you like to see references in a non-fiction book?

The writing in my book is like that in my science-based blog posts. I am basing it on lots of references and papers, but I am trying to frame the scientific questions with real-life stories from my experience and that of other parents.

When I submitted my book proposal, the peer reviewers responded that they thought an evidence-based book backed by references would be a unique and helpful resource to new parents. And based on the responses from you, the readers of my blog, I think you value this as well. So providing references and making them accessible to the reader is important to me.

When my editor and I were going over the book contract, the topic of how to handle references came up. Initially, he thought that I should avoid in-text references – either noted by author or by number. That is, he didn’t expect sentences like this made-up one: “In one surprising study, researchers from the University of Amazing found that children were more accepting of new foods when they XXX.⁵⁷” Instead, he recommended simply providing a list of references, by chapter, at the end of the book, without necessarily linking each reference to the text describing it. After some discussion, he said he was open to me using in-text citations, but I also agreed to give some thought to different options.

I’m actually really uncomfortable writing about science without in-text citations. I’m used to science writing where you provide a reference for just about every single statement you make. That’s how I learned to write for scientific papers, and on the blog, I’ve continued with this style without much thought. In this style, I’m saying, “Don’t take my word for it – this is coming from these scientists who researched the question.” I’m not writing this book from a place of authority but rather from one of curiosity. I’m not claiming to be an expert with all the answers but rather a person who has questions and is willing to dig for the answers. And as a reader, I like being able to flip to the reference list at the end of the chapter or the back of the book and see the authors, title, year, and journal where a particular study was published.

I think that the argument against in-text references is that they are distracting from the narrative. I do think that references providing names and dates can be distracting, but I personally think that superscript numbers can do the trick without taking away from the story. Even so, I understand the point that the story needs to stand on its own even if the reader never checks references. Perhaps not providing in-text references would force me to be more selective about the references I choose and to build the story of a particular study more fully. And it might make the book feel more accessible to a reader not accustomed to this style.

I also admit that my resistance to writing without in-text references comes in part from my hesitancy to step outside my comfort zone. It could be that references are a sort of crutch to me, and that my writing would improve without them if I was willing to work on this.

Going through the books on my shelf right now (those that relate to parenting and science but are written for a lay audience), I see a few different ways of handling this question.

1. A “Notes” section – without in-text markers – followed by a bibliography with full citations. Examples of this format:

NurtureShock, by Po Bronson and Ashley Merryman, is a really excellent book that makes science come alive within an easy narrative. I really admire this book, so I paid close attention to this format. There are no in-text references or footnotes. Important studies are described in detail, and sometimes the journal and year of publication are given within the text. A Notes section at the end of the book provides references backing assertions within the chapter. These are not marked within the chapter, but if you were reading along and wondering what evidence stood behind a particular statement, you might find a paragraph in the Notes describing and listing several studies by author and date. You could then proceed to the “Selected Sources and References” at the back of the book listing full citations by chapter. Finding the papers behind a given statement in the chapter thus requires a two-step process – checking first the notes and then the reference list. But the text of this book flows so easily that you want to keep reading, not check references. I think that’s a good thing.

The Panic Virus by Seth Mnookin, another book that I admire for its sound science and gripping narrative. The notes and bibliography of this book are nearly 100 pages long. Notes are not marked in the text but are listed by page number in the Notes section.

How Eskimos Keep Their Babies Warm by Mei-Ling Hopgood – (I reviewed this book here.) Notes are listed by page number, and it also includes a bibliography.

2. A “Notes” section – with superscript numbers as in-text markers – followed by a bibliography with full citations. Examples of this format:

Bottled Up by Suzanne Barston – Gosh, I’ve been meaning to write about this book, but I’m afraid I need to reread it first since now its been too long. Great book, though.

Bringing Up Bebe by Pamela Druckerman – There’s more science in this book than meets the eye.

Your Baby’s Best Shot by Stacy Mintzer Herlihy and E. Allison Hagood

3. Just one reference list at the end of the book, with in-text markers for sources.

The Science of Parenting, by Margot Sunderland. I also paid close attention to this book since my book may be competing in a similar market, and there are things that I both like and dislike about this book. Sunderland doesn’t tell us much about the studies she cites but instead uses them to back narrative text providing advice to parents. In this case, I really appreciate the in-text citations, because sometimes I’ve tracked down her references and found that she’s stretched the interpretation of a study and made a few conceptual leaps to link it to her statement. I think this illustrates one danger of in-text citations. It gives the look of authority, but perhaps it also allows the author to take more liberties with her interpretation, because she doesn’t actually have to tell you much about the studies backing her statement. If you’re wondering, you can go look it up, but many readers won’t have the time or resources to do this.

The Fourth Trimester by Susan Brink: I just received a review copy of this book and haven’t yet read it. In-text citations are given as superscript numbers, and all references (including interviews and correspondence) are given in one “Notes” section.

4. No in-text citations and one reference list available. This style seems to be adopted mostly by experts in their fields, who likely feel comfortable giving advice without backing it with research. (This isn’t me!)

Child of Mine by Ellyn Satter – This is my favorite guide to feeding children, and it is evidence-based to boot. She also has many appendices on important topics (like “Nutritional Principles for Baby Formula” and “Children and Food Acceptance: The Research”), written in more technical language and really geared for the parent who wants to know more about the research behind her recommendations.

Beyond Baby Talk by Kenn Apel and July Masterson – (I reviewed this book here.)

Brain Rules for Baby by John Medina – no printed references in the book, but a note on a single page at the back of the book refers the reader to a website that provides “extensive, notated references.”

Do Chocolate Lovers Have Sweeter Babies? By Jena Pincott – (I reviewed this book here.) One section at end has “Sources” listed by chapter.

Maybe you can help me figure out how to handle references. Can you check some of your favorite science books to see how they do it? What style do you prefer? Do you even check references when you’re reading a book like this?