Chris Schulz Published

Understanding How Babies Sleep

A close up of a sleeping baby in her crib. Her face is blurred slightly, while her hand is in focus. She wears a pink polka dot onesie, and her sheets feature light blue and white stripes.
Understanding how and why babies sleep differently than adults can help parents and other caregivers ensure better sleep for the whole family.
Photo courtesy of Monkey Business/Adobe Stock

Sleep is a key part of both mental and physical health for everyone. But for many parents, ensuring their baby is getting good sleep can be frustrating and elusive.

In the latest installment of our new series “Now What? A Series On Parenting,” reporter Chris Schulz speaks with Dr. Paul Knowles, a Marshall Health neurologist and assistant professor at Marshall University Joan C. Edwards School of Medicine, about infant sleep.

This interview has been lightly edited for length and clarity.

A portrait balding man wearing glasses, pink dress shirt with collar button undone, and a patterned blue tie standing at the second floor railing of an interior antechamber of a building.
Dr. Paul Knowles, Marshall Health neurologist and assistant professor at Marshall University Joan C. Edwards School of Medicine.

Courtesy of Marshall Health

Schulz: Why is sleep so important for everyone?

Knowles: We are built to spend a third of our time alive asleep, a third or more. And unfortunately, as a culture, we have de-emphasized the need for sleep. Everybody’s like, “Well, I have all these things to do.” And the thing that typically gets whittled away is sleep. But sleep is important because it restores you physically and also restores you mentally. 

There are a number of studies that show that sleep is probably important in learning, that people who study for a test and then get a good night’s sleep are much more likely to recall all the facts and do better on the test than somebody who stays up all night and crams. There’s lots of theories and questions, and we certainly don’t fully understand exactly what it does. What purpose does dreaming serve? Some people feel it’s your way to work through emotions and things. It’s clear that sleep serves a major restorative function. But in addition to that, it’s important in learning, how we’re organizing your brain in your mind and things like that.

Schulz: Can you tell me a little bit about why infant and child sleep is different from adult sleep?

Knowles: Anybody who’s had a baby knows it’s different. Particularly newborns don’t sleep like the rest of us. As an older child or an adult, you go through sleeping, you move into the lighter stages of sleep and eventually get to deeper stages of sleep and then into REM sleep or dream sleep. Newborns move immediately into REM sleep. Their neurological systems are not mature enough that they have prolonged sleep the way we do. 

Most “normal people” sleep eight hours at night, seven to nine hours at night as sort of a single block and that’s our sleep for the day. Infants sleep 16, 17 hours a day, but rarely more than a couple hours at a time. Sometimes they’ll nap and only be five, 10, 15 minutes, and sometimes they’ll nap and it’ll be four hours. The typical newborns have like seven or eight cycles through the day of wake and sleep. They sleep in little, little cat naps through the 24 hour cycle, rather than one single long-term block of sleep that you do as an adult. That matures over the first three to six months. Usually by three to four months, they’re starting to sleep the majority of the night. You get a good five or six hour block where you get sleep, and usually by six or seven months, they’re basically sleeping through the night. 

Of course, one of the major issues is, the babies never read the texts. You have lots of families who come in and complain that their one-year-old still isn’t sleeping through the night. I had a colleague of mine years ago, we were complimenting him on how nice his teenager was, and he says, “The last time the boy did anything right was he slept through the night two weeks after he was born.” So there’s wide individual variation, but you can’t really expect a newborn. Some parents get frustrated when their two-month-old isn’t sleeping through the night yet. And it’s because physiologically, they’re just not there yet. Their systems haven’t matured to the point where they can sustain sleep for that long.

Schulz: Is there anything that parents can do to help that process along, or is it just a question of waiting?

Knowles: I mean, there’s a little bit but to some degree, you have to wait for the baby to mature. It’s the same thing as, the baby can’t walk until the baby has the strength and the coordination to put the muscles together and perform the action. It’s the same thing. You’re not going to be able to train your one month old to sleep through the night. You might be one of the lucky ones where the baby really does, at an early age, get a bigger block, and you get more consolidated sleep yourself. But most parents learn to sort of sleep when the baby does, and their sleep is more disruptive than we’re used to, and we don’t feel as good. But again, over three or four months, you start to get longer blocks. 

I think the parents, particularly as the child gets to be older, keeping a good routine really helps to consolidate that. I see parents and unfortunately, again, it’s a part of our culture – and this is talking typically a little bit more about the older kids – where the kids over the course of the week may sleep in three different places. They may spend a couple of days with the grandparents, a couple of days with mom, a couple of days with dad if mom and dad are separated, divorced. And everybody has a different schedule. Then they’re complaining that their children are having sleep issues. Well, part of that is because grandma’s trying to get them to sleep at 7 p.m., and mom’s letting them stay up to 10 p.m. And dad doesn’t care if they want to stay up and play video games to 1 a.m., he’s fine with that. So they have a different schedule everywhere they go and they’re having problems training their body what their routine should be.

Schulz: Does the space itself also contribute? Because I know especially for infants, there’s a lot of discussion about when to move them out of the bassinet and into the crib into a different room, etc. Does that have an influence on children generally, as much as having a regular schedule and routine does?

Knowles: I think probably the routine is a little bit more important. Obviously, you want a comfortable space. As a culture, we tend to discourage, you know, co-sleeping where the baby’s actually in the bed with you. My big issue actually with them having them in the same room is it’s very convenient for mom and dad, but sometimes mom and dad are disrupting the kids’ sleep. If somebody is a loud snorer, or has something like sleep apnea and is making loud noises and they’re disrupting the child’s sleep. So that becomes a component of trying to get them to sleep through the night, if their parents are actually contributing to the disruption.

Schulz: Sleep training, is there an evidence base to support this approach to encouraging independent sleep? What can you tell me about this process?

Knowles: There are several different mechanisms that are talked about. Perhaps one of the most well known is their Ferber method. Dr. Ferber wrote a kind of textbook, but it’s really actually written for the parent. It’s gone through multiple editions and I’ll be honest, I don’t know when he first wrote it. It was the ’70s or ’80s. He talks about methods to try and help train your child to go to sleep without you, to be able to put them down. Let them get used to the bed, let them self-soothe.

He talks about if they wake up and they’re fussy, you don’t go in and you don’t console them, you go and check on them and maybe briefly console if they’re really ramping up, but then you leave before they’re asleep so they eventually learn that they’re going to have to fall asleep in bed themselves. There are some studies showing that these sort of mechanisms work. And there’s several somewhat variable ways to do it, but people talk about Ferber-ising the bedroom routine, and his is probably one of the most famous ways to do it.

Schulz: So would you say that push back in recent years has more to do with parents and other caregivers, just not really being able to tough out that period of adjustment where the baby is expressing its displeasure?

Knowles: Each individual case is different and sometimes, there may be other issues going on. I think a lot of times it is difficult for the parents learning, too. And I’ll be honest with you, when my kids were little, and I’m in my 60s now, but when I had little kids, my first one, my wife fussed at me because the baby started crying, I started getting out of bed, she says, “Just leave her.” And I said “She’s crying.” She says, “Just leave her.” And sure enough, you know, five minutes later, she fussed for a couple minutes then rolled over and fell back asleep and I didn’t have to get up.

But you know, the baby had trained me. When she was little, she fussed, because she was either wet or she needed to feed. So I was sort of trained, “Oh, she starts to fuss, she needs something changed or something done.” My wife was the one to say, “Better let her soothe herself if she will.” 

Schulz: It’s always reassuring to hear an expert say that they go through the same issues as everybody else. 

Knowles: Oh, yeah. It’s always different when it’s your kid. As somebody who trained in pediatrics, you learn that at a relatively young stage, it’s one thing to sit there and tell the parent, “This is what you got to do.” Then when you’re living through it yourself, it’s trying to remember what you tell everybody what to do, sometimes it’s hard.

Schulz: I wanted to jump back to a statement that you made earlier on in our conversation. It always fascinates me, I spoke to a pediatrician a few weeks ago who told me that the way she looks at it is the first three months of a baby’s life is basically the fourth trimester because their neurology and their brains are so underdeveloped, and then they still need that time to finish the work that was started in the womb. Does that bear true for you in your work with infants and what you’ve seen over the years?

Knowles: I think that that absolutely is true. In the first three or four months, it’s really obvious. Obviously our brains are changing for much longer than that. We make new neuronal connections well into adolescence. Our brain grows and changes over the years, but particularly the first year. 

The easiest example of that is white matter. It’s called white because of the presence of what we call myelin, which is the sheath around the nerves, that not only protects the nerves, but also actually impacts the functions of the nerves. Myelinated nerves tend to send impulses faster than unmyelinated nerves, and not all nerves are myelinated. But if you do an MRI on a newborn, there is very little myelin in the brain, there’s only a couple places. And then if you do repetitive MRIs up to about a year, or just over a year, you see increasing amounts of change, a maturational change in that brain. 

You can see that on a physical basis by the myelin developing and growing in the brain that clearly correlates as you get that more myelin, you get more control. So the baby suddenly isn’t just waving their hands around, but now is starting to reach for objects, no longer does a Palmer grasp, but does pincer grasp, is no longer just making simple sounds, but is making complex sounds. That all correlates together. Particularly the first few months, but even that first year, year and a half, there’s a dramatic maturational change in the brain that occurs. It has an impact on just normal development, but also maturation of your sleep habits and everything else.

Schulz: Is there anything else that I haven’t given you an opportunity to discuss, or something that you’d like to highlight?

Knowles: I think it’s what we started with: sleep really is important. As a culture, we have tended to de-emphasize how important it is particularly for the young developing brain. Having that opportunity to sleep and keeping a normal cycle really does improve maturation and development of the brain.

A light blue background with text that reads, "Now What? A Series On Parenting, From WVPB." On the blue background is a silhouette of a pink stork holding a baby in a bundle. There are also artistic half circles on the top and bottom of the graphic that are yellow, blue and pink.