Category Archives: Sleep

Introducing Solids and Baby Sleep: Yep, Early Solids Improve Baby Sleep After All

Don’t give your baby solids until 6 months of age. This is the unambiguous advice of the world’s most highly regard medical organizations, including the American Academy of Pediatrics, the UK’s National Health Service, and the World Health Organization.

Ignore the “mistaken” belief that introducing solids earlier will help your baby sleep better. Early solids could have the opposite effect, worsening your baby’s sleep, according to popular parenting sites like Kelly Mom and the Baby Sleep Site.

Or so we have been told.

It turns out that the claim that solids don’t help baby sleep was based upon the shoddiest of studies–small, non-randomized, poorly controlled–like this one, which simply looked at whether babies were eating solids and how well they slept.

(To be clear–I am not trying to knock this research as research. Small exploratory studies can be very useful for hypothesis generation and deciding on which large studies to run, but the stuff of sound public health pronouncements they are not.)

Now, we finally have much better data, from a randomized trial of over a thousand babies. And surprise, surprise, your mum (or in my case, my mother in law) was right all along: Introducing solids early, at around 3 to 4 months, does improve babies’ sleep. Not just then, but for their entire first year.

The Details

The new study is a secondary analysis of the UK-based Enquiring About Tolerance (EAT) randomized clinical trial, a trial whose main goal was to assess whether early solids lowered the risk of food allergy.

In the trial, researchers randomly assigned 1,303 exclusively breastfed infants to either begin solids at three months (the experimental group) or at around 6 months of age (the control group).

Parents in the experimental group began feeding their babies solids at around 3 months of age, with specific instructions to expose them to six common food allergens (eggs, peanuts, white fish, cow’s milk, wheat, and sesame seeds).

The randomization was highly successful. Nearly all babies in the early introduction group began taking in solids by 4 months of age, whereas almost none of the control babies started solids until after 5 months of age. Notably, nearly all these babies continued to be breastfed, almost none received formula.

Although the EAT trial’s original purpose was to determine if early solids would help prevent food allergies, the study also carefully assessed the babies sleep. Each month, parents reported how long their babies slept at night, how often they awoke at night, and if they felt their babies had mild or severe sleep problems. They also described where their baby slept and how they put their babies to sleep.

Thus, this study represents the largest, carefully constructed randomized trial of how solids affect infant sleep ever performed.

So what did they find?

Babies who received solids early, starting around 3 to 4 months, slept better than controls. They slept a tiny bit longer each night during their first year of life (an average of 6-7 minutes overall, with the biggest difference–17 minutes longer each night–seen at 6 months of age). They were also about 10% less likely to wake up at night. So good, but not really much to write home about.

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Where early solids packed the biggest punch, however, was in preventing sleep problems. While only a small percentage of babies had sleep problems (fewer than 5% overall), control babies were much more likely to be problematic sleepers.

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As shown in the graph below, severe sleep peaked at around 9 months, and then dropped off sharply at a year (good news for many a bleary-eyed sleep beleaguered parent).

Most strikingly, parents of early introduction babies were far less likely to say their babies had mild or severe sleep problems throughout their first year of life–long after the controls were also taking in solids. It appears that early solids helped babies consolidate their nighttime sleep earlier, and this benefit persists throughout infancy.

This latter point was surprising to me, but appears well supported. In fact, the more solids experimental babies ate earlier, the better they slept. (This was a follow-on analysis, and not randomized, but it does lend further support to their main findings.)

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The Bottom Line

So, does this study mean we should all give our babies solids early to help them–and us, let’s not forget us!–sleep better?

By itself, probably not. The effects on sleep are pretty small, overall, (6-7 minutes extra sleep a night; about one less night awakening a week). And before we run completely in the opposite direction and overinterpret these findings, I would really love to see at least one other randomized trial examine the same question.

And we need to note that the babies who slept best in this study (as we already know) were not co-sleeping, slept in their own rooms, and went to sleep by themselves, without parental assistance. These practices had a much bigger impact than solids on baby sleep and remain the foundation for helping your baby sleep well.

That said, let’s step back a second and consider the larger context. Many studies now suggest early solids lower the risk of allergies. This is why many medical organizations that focus specifically on allergies recommend starting solids earlier (4-6 months) than their umbrella counterparts (6 months)–creating schizophrenic, headache-inducing advice for well-meaning parents.

For me personally, speaking as a parent, I would look at these findings and choose to start giving my baby solids at around 4 months of age.

(Introducing peanuts early lowers the risk of peanut allergies. Although the EAT trial did not actually show significantly lower risk of food allergies, there was a trend in that direction.)

As I have written about earlier, the recommendation to breastfeed exclusively for 6 months really only makes sense for women living in developing countries, where access to clean water and safe food sources can be limited. There are no demonstrated benefits for women living in developed countries like the US and the UK. It’s past time for medical organizations to reconsider this misguided blanket advice.


Back sleeping and stillbirth revisited: A reason for caution, or a few extra pillows

As longtime readers of my blog know, in 2011, carrying my first child, I became obsessed with the question of whether pregnant women could lie on their backs–either for short periods of time, such as during a yoga class, or while asleep at night.

Several OBs told me to avoid lying on my back. But their justifications were murky, and their advice conflicting. Not a one could point to a single published study backing this advice up. And when asked at what point in pregnancy I needed to start avoiding back sleeping, their answers were all over the place. One told me it was verboten from 4 months on, another from 5 months on, and the third claimed I should worry only in the last month or so.

Sleeping with a bowling ball-sized stomach is challenging, to say the least. At the same time, groundless sleep prohibitions with vague but terrifying warnings that you might harm your baby are immensely frustrating, and yet almost impossible to disregard.

But while in 2011, these dire warnings sounded like a yet another pregnancy prohibition in search of a reason (no Brie, not a drop of alcohol, keep your heart rate below 140 while exercising, etc., etc.), several studies (one from Australia, two from New Zealand, one from Ghana, and the latest, from the UK) have since found that back sleep may indeed be linked to what is termed late stillbirth, or pregnancy loss after 28 weeks.

The science of back sleeping and stillbirth

Continue reading Back sleeping and stillbirth revisited: A reason for caution, or a few extra pillows

Surviving the First Year: Two books to help you understand baby’s sleep

For most new parents, sleep becomes an obsession, their most precious commodity. They will happily trade exercise, sex, and time with friends for just a shot at catching some Z’s–kind of like how a rat with ad libitum access to cocaine will happily forgo food.

Continue reading Surviving the First Year: Two books to help you understand baby’s sleep

The Middlemiss Study Tells Us Nothing About Sleep Training, Cry-It-Out, or Infant Stress

Last week, I wrote a post about sleep training and stress, in which I argued that everything we know about stress suggests that sleep training is not harmful.

In response, some people objected that sleep trained babies continue to experience elevated cortisol and significant distress, even after they have stopped crying. In their view, sleep training teaches babies that crying does not help. They haven’t learned to self-soothe or to fall asleep on their own, they’ve simply given up.

What a heartbreaking thought. And one that surely strikes fear in the heart of many parents.

So it’s important to realize that this claim comes from a single small and deeply flawed study of 25 babies, led by Wendy Middlemiss, a researcher at the University of North Texas’s College of Education.

Continue reading The Middlemiss Study Tells Us Nothing About Sleep Training, Cry-It-Out, or Infant Stress

Critics of Cry-It-Out Fundamentally Misunderstand How Stress Affects the Brain

Because whether or not to sleep train can be such a fraught decision for new parents, I wanted to share my sleep training story, and to explain why, given everything we know about stress, the argument that sleep training causes long-term harm doesn’t hold water.

Sleep Training My Son

When my son was 4.5 months old, I decided to sleep train him. Even by baby standards, my son was not much of a sleeper. He’d snooze for at most 4 or 5 hours, and then wake up every hour like clockwork, wanting to nurse but not wanting milk, popping on and off my breast and screaming in frustration.

I had gone back to work a month earlier, so napping to catch up on sleep was out of the question. Worse, I was commuting an hour to the office each way.

By then, I had reached the end of my sleep deprivation rope. I was so tired I could barely string two thoughts together. I had to coach myself through even mundane tasks like checking out at the grocery store. Say hello to the cashier. Take out your credit card. Pick up the grocery bags. Leave.

I was terrified every time I got into my car to head to work that I would nod off at the wheel and kill someone, quite possibly myself. I joked with coworkers that driver’s licenses should be temporarily suspended for new parents, but the situation really wasn’t funny.

So there I was the first night of sleep training, dripping sweat as I listened to my son’s cries. Minutes ticked by, each seeming longer than the last. I pondered whether the Ferber method included soothing every five minutes just so that you would realize only five minutes had passed.

But I was determined to stick this out, to get it done. Doing it halfway was worse than not doing it at all, I reminded myself over and over. If I were to give in, I could teach my son that crying for 30 minutes was what it took to get mommy to pick him up.

That night, he woke two more times, but never again cried more than 15 minutes. The next night, he cried for 10 minutes at bedtime, conked out, and slept until morning. That morning we greeted each other with a smile, and for the first time since his birth, I really felt like smiling at his freshly woken little face.

Although by all appearances, sleep training went well for us, some critics of cry-it-out methods would contend that I was an inadequate parent who had permanently harmed my son by leaving him alone to cry.

The Cry-It-Out Controversy

“An emotionally available parent would probably not let their baby cry it out,” claims Dr. Teti, a researcher at Penn State.

Dr. Narvaez writes in Psychology Today:

“Letting babies get distressed is a practice that can damage children and their relational capacities in many ways for the long term. We know now that leaving babies to cry is a good way to make a less intelligent, less healthy but more anxious, uncooperative and alienated persons.”

When someone tells you that you have permanently damaged your child, it’s hard to shake off, no matter how much happier you and your baby seem once you start getting some solid rest.

Thankfully, as someone who has studied the effects of chronic stress in animals and in people, I knew that claims like Dr. Narvaez’s are not supported by data and instead rest on a fundamental misreading of stress research.

Studies on Cry-It-Out

Studies involving cry-it-out methods find no ill long-term effects for babies, and big benefits for parents. In one study, rates of depression in mothers dropped from 70% to 10% after sleep training.

Critics of cry-it-out methods argue that these studies are flawed–they don’t have the right measures of harm, they fail to determine whether the parents actually used cry-it-out methods to sleep train their babies, and they rely on parents’ reports instead of observation.

Admittedly, some of these criticisms of sleep training research are fair. Sleep training research is hard to do, especially since researchers can’t exactly force parents to sleep train little Johnny, or prevent parents from doing so.

That said, there’s no evidence in humans–none–to support the view that sleep training is harmful. If there were, we’d have heard about it.

So what the critics of cry-it-out argue, really, boils down to this: They know that sleep training is harmful, because they know stress is harmful to babies.

The problem with that argument? All stress is not created equal. We were designed to handle short-term stress. Where we humans, and other animals, run into trouble is when stress becomes chronic.

Short-Term Versus Chronic Stress

In terms of their effects, the difference between short-term and chronic stress is one not of degree, but of kind. Short-term stress enhances memory; chronic stress impairs it. Short-term stress boosts the immune system; chronic stress weakens it.

(Seeing short-term and chronic stress as fundamentally different is not just my own heterodox personal take. This is the view of people who study stress for a living, including the renowned stress neuroscientist and primatologist Robert Sapolsky, professor of Neurology at Stanford University, who writes extensively about this key distinction in his excellent book, Why Zebras Don’t Get Ulcers. The American Academy of Pediatrics emphasizes this distinction in its statement on early life stress. And the Harvard statement on child development, cited by Dr. Narvaez herself in her Psychology Today piece, makes a point of distinguishing between short-term and long-term stress.)

The Effects of Stress in Early Life

Short-term stress mobilizes us for action–the classic fight-or-flight response. Adrenaline and cortisol pump through our veins; our bodies brim with energy; and mentally we become hyper-focused.

But these short-term adaptations are harmful when switched on for too long, especially when we are young. Scores of animal and human studies show that early life stress, such as severe early social deprivation, leads to long-term changes in the brain, cognitive and social problems, and heightened susceptibility to anxiety, depression, and drug abuse in adulthood. Chronic stress is toxic.

But from this can we conclude that all early stress, even short-term stress, is harmful?

No. Absolutely not. In studies of short-term stress early in life, occurring within the larger context of a close caregiver-infant relationship, none of these ill effects are observed.

In fact, young monkeys exposed to early short bouts of stress, such as brief periods of separation from their mothers, become more resilient to future stresses. They are less anxious and have less extreme physiological reactions to stress later in life. This phenomenon is so consistent that researchers have labelled it stress inoculation.

My Take

So where does that leave us? A little stress, even in infancy, is fine, if not beneficial, but too much for too long is very, very bad.

Do we know exactly where sleep training fits in this spectrum? Just how much stress does a baby experience during cry-it-out?

The short answer is that we don’t know for certain. Everything we do know, however, suggests that this amount of stress, in the context of a warm, loving family, is just fine.

To see why, let’s return for a second to the American Academy of Pediatrics statement on early life stress, which provides examples of the types of stress children can withstand, provided they occur within a broader context of loving, supportive relationships. These include “the death of a family member, a serious illness or injury, a contentious divorce, a natural disaster, or an act of terrorism”. By comparison, sleep training seems pretty mild.

But I would go further. I believe that sleep training is not only not harmful, it is beneficial. Successful sleep training can decrease depression and chronic stress in the parents, and this benefits parents and their babies. Unlike sleep training, having a depressed mother during early childhood has been shown, repeatedly, to be linked with worse long-term outcomes for children.

Which brings me to what I find most troubling about the claims of sleep training opponents: Their zero-sum take on parenting. Worrying about your own sleep needs is selfish, they not so subtly imply. Any time you fail to put your baby’s needs before your own, you are potentially doing him harm.

What a narrow, cramped view of parenthood.

No one would ever dispute that parenthood entails enormous sacrifices, especially when your children are young and their need for you feels so endless and all-consuming.

But I think that because parenthood, and motherhood in particular, is so often judged in terms of self-sacrifice, we tend to forget that a primary job for parents is to be strategic.

As parents, we must weigh short-term costs against long-term harms, because our children cannot. We have to consider the risk of a few nights of stress and unmet needs against the risk of a car accident or job loss, and against the serious physical and emotional toll of chronic sleep deprivation on the entire family.

We can forget, too, that the parent-child relationship is one not only of sacrifice but also of profound mutual benefit. You being a whole, fulfilled individual with a solid relationship with your partner, meaningful social ties, and a sense of purpose enriches your world and your child’s world. You being a well-rested, healthy, and happy parent is good for you and good for your child.


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Darcia Narvaez. Dangers of “Cry-It-Out”: Damaging children and their relationships for the longterm. Psychology Today. 2011.

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Back Sleeping During Pregnancy and the Sydney Stillbirth Study

Pregnancy can be cruel. Just when you are at your most swollen, bloated, and exhausted, sleep proves frustratingly elusive. Every night, you toss and turn, trying to find a comfortable position, your back aching, and your belly pressing down on your bladder. And then, as you finally start to drift off, you realize you need to pee.

To make matters worse, despite having an enormous bowling ball attached to your stomach, you are told you cannot sleep on your back:

“After 16 weeks of pregnancy, experts advise women to not sleep on their backs, but rather should lie on their sides, ideally the left side.” – mamalette

Who came up with this idea?

This advice stems three studies that have linked back sleeping with late stillbirth (pregnancy loss after 28 weeks). (Interestingly these warnings predated the three studies, so they are not exactly the reason women are told to avoid back sleeping)

I described the first two studies, one conducted in Ghana, the other in New Zealand, in an earlier post, and concluded that not only did they provide no reason for alarm, they certainly do not justify blanket advice again back sleeping.

In 2015, a third study came out linking back sleeping with late stillbirth. Does it change the overall picture?

Continue reading Back Sleeping During Pregnancy and the Sydney Stillbirth Study