Baby sleep patterns: An evidence-based guide

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What does normal infant sleep look like, and how does it change over the first 12 months? Baby sleep patterns vary from individual to individual, and from one culture to the next. So there isn’t any one sleeping schedule that all babies follow. There isn’t a universal number of “sleep hours” that every infant needs, or a precise age at which all babies suddenly begin to “sleep through the night.”

But scientific research can help us understand the general trends, including these:

  • Newborn sleep is often disconnected from the natural rhythms of day and night, but we can help babies develop mature circadian rhythms by exposing them to the right environmental cues.
  • Baby sleep cycles feature lots of time in “Active Sleep,” a stage of light sleep that is similar to REM sleep in adults, but a lot more restless. As a result, babies awaken more easily.
  • Young babies need to awaken frequently to feed, and many babies don’t reach the milestone of sleeping for at least 5 hours at a stretch until they 5-6 months old (or older).
  • Although infant sleep is influenced by genetics, it’s also shaped by caregiving and other environmental factors.  Parents can use their knowledge of sleep science to minimize disruptions, and help babies learn to fall asleep without lots of attention and fanfare.

In this article, I provide a timeline of baby sleep patterns, followed by more detailed look at the ways in which infant sleep differs from adult sleep. I will cover circadian rhythms and baby sleep cycles, and answer questions like “how much sleep does a baby need?” and “when do babies start sleeping through the night?” At the end, I offer evidence-based tips for avoiding sleep problems, and supporting the development of mature sleep patterns.

Baby sleep patterns by age: A concise, developmental timeline

0-3 months. Newborns sleep in short bouts scattered throughout the 24-hour day. As the days pass, they gradually develop a tendency to sleep more at night.

How much sleep do these babies get overall? It can vary quite a bit between individuals. During the first 4 weeks postpartum, infants may sleep as much as 16-17 hours every 24 hours. Across the first 3 months postpartum, about half of all babies get between 13 and 16 hours of sleep every 24 hours (Sadeh et al 2009). 

And what does sleep look like during the first 3 months? Overall, it’s light and restless. When newborns first doze off, they typically pass directly into a baby version of REM (rapid eye movement) sleep — a sleep stage that is associated with frequent twitches, and other physical activity. Babies are easily awakened while in REM, and, as I note below, they spend a large portion of their total sleep-time in REM. Learn more in my article about newborn baby sleep patterns.

3-4 months. Baby sleep patterns are becoming more adult-like. Infants no longer plunge directly into REM after falling asleep, and their sleep cycles begin to include longer stretches of peaceful, slow-wave, “deep” sleep (Schechtman et al 1994).

In addition, babies are more likely to sleep for extended periods at night. For example, in one study, approximately 50% of parents reported infant sleep bouts lasting 5 hours or more (Henderson et al 2010). But multiple daytime naps are still common, and there is still a lot of individual variation. For most babies this age, total sleep duration is likely in the range of 12-16 hours.

5-6 months. Around this age, most parents report that their babies are sleeping without interruption at night for 5 hours or more, and many claim their babies sleep for more than 10 hours at night (Mindell et al 2016; Iglowstein et 2003; Jiang et al 2007).

Nevertheless, it’s not unusual for parents to report that their babies awaken at least once during the night, and some babies don’t settle into 5+ hour sleep bouts until they are considerably older (see below). Babies typically take several naps during the day, and average total sleep duration remains in the range of 12-16 hours.

7-12 months. If your baby still isn’t sleeping for at least 5 hours at a stretch, you’re in good company. In one study of American infants, more than 15% of parents reported that their 12 month old babies hadn’t yet reached this milestone (Henderson et al 2010).

But for most families, nights have quieted down. It isn’t that these babies don’t experience night wakings. On the contrary, it’s normal for infants this age to awaken 3-4 times each night. But many babies have learned to fall back to sleep quietly on their own, so that their parents aren’t even aware that their infants had awakened (Goodlin-Jones et al 2001; Dias et al 2018).

By the end of the first year, babies tend to spend less time napping. But naps appear to remain helpful, and babies typically take one or two each day. Most babies continue to get sleep approximately 12-16 hours every 24 hours. 

Digging deeper: What makes infant sleep different from our own, and how can we use this information to foster the development of mature sleep patterns?

Mature sleep is patterned in many ways. First, there is the overall scheduling of sleep across the 24-hour day. Adults and older children do the vast majority of sleeping at night, because their circadian rhythms are synchronized with setting of the sun.

Next, there are patterns of brain activity that unfold during a given bout of sleep — the sleep stages and sleep cycles that repeat themselves as we slumber. These are useful to understand, because some sleep stages are “deeper” than others, and there are points during our sleep cycles where we are more likely to wake up. This is true for adults and babies alike.

Then there are developmental patterns in the length of time we spend sleeping. How much sleep do we actually need? How long do we remain asleep at any given time? As we’ve already seen, newborns begin life needing many hours of total sleep, but they never stay asleep for very long. When can parents realistically expect their babies to sleep quietly at night — without frequent nighttime awakenings? What factors affect the developmental timeline? And what can parents do to support sleep development? Let’s dive into the details.

Circadian rhythms: How long does it take for babies to synchronize with the natural, 24-hour day?

Young babies are notorious for sleeping and waking at awkward times. In part, this is because their circadian rhythms — recurring, 24-hour cycles of physiological activity — aren’t synchronized with the natural rhythms of daylight and darkness.

You may have heard that it takes 3-4 months for babies to develop mature circadian rhythms. But research confirms that the timing varies, and that babies synchronize sooner when we provide them with the right environmental cues.

Light has the biggest impact on your baby’s “inner clock,” so use it wisely.

During the day, expose your baby to natural, bright light. And as evening approaches, dim the artificial lights, and take care to avoid nighttime exposure to blue light, which is especially disruptive of sleep. Research suggests that newborns sleep for longer stretches at night when their parents stick with a policy of “lights out” after 9pm (Iwata et al 2017).

In addition, involve your baby in your daily activities, and avoid the temptation to turn nighttime feedings into social events.

When you attend to your baby in the middle of the night, be soothing, but avoid engaging your baby with eye contact and conversation. Keep the lights off, and your behavior low key.

Sleep stages and sleep cycles: How do baby sleep patterns unfold over the course of the night, and when are infants most likely to awaken?

To answer this, it helps to review what adult sleep is like. 

For us, sleep isn’t a single continuous state of coma-like unconsciousness. We pass through a series of sleep stages, beginning with light stages of non-REM sleep, progressing to deep sleep, and ending with rapid eye movement sleep, or REM — the sleep stage associated with busy brain activity, dreaming, and the loss of muscle tone. We don’t move around during REM unless we suffer from certain sleep disorders.

The whole sequence takes approximately 90-100 minutes, after which we either awaken or repeat the cycle. Sleep lab research shows that we’re especially prone to awaken during or immediately after REM (Akerstedt et al 2002).

But throughout each sleep cycle, we also experience multiple arousals — brief, partial awakenings. These are a normal part of sleep, fleeting “check ins” that help the brain keep tabs on potential threats. If there is nothing to attract our interest or concern, the arousal process is aborted, and the brain goes back to sleep.

For infants, things are much the same. 

Babies experience distinct sleep stages, including an infant version of REM. They also experience many brief arousals during the night, fleeting moments of drowsy wakefulness that you might not even notice (Grigg-Damberger et al 2007; Montemitro et al 2008).

But baby sleep patterns differ in notable ways.

As I explain in my article about baby sleep cycles, REM sleep in young infants takes a pretty peculiar form. Whereas we adults don’t move around much during REM, babies can be very restless — so much so that this “infant” type of REM is sometimes called “Active Sleep.”

In addition, young babies experience sleep stages that don’t have any precise equivalents in adults. These include indeterminate, transitional states of sleep, as well as a less restless, non-REM sleep stage dubbed “Quiet Sleep.”

Moreover, infant sleep cycles are shorter — on average, about 50-60 minutes long (Jenni and Carskadon 2000; Jenni et al 2004; Grigg-Damberger 2017). And for the youngest babies, the average sleep cycle looks something like this:

  1. Active Sleep (REM)
  2. Indeterminate or Transitional Sleep
  3. Quiet Sleep
  4. Indeterminate or Transitional Sleep
  5. Active Sleep
  6. Brief waking (1-2 minutes)
  7. Indeterminate or Transitional Sleep

In other words, newborns tend to begin a sleep bout in REM, and then transition into “Quiet Sleep” before returning to REM (Parslow et al 2003). In general, babies don’t develop more mature-looking sleep cycles (that begin with a light stage of NREM sleep stage, and include a stage of deep, “slow wave” sleep) until they are roughly 3-6 months old (Grigg-Damberger et al 2007; Grigg-Damberger et al 2016).

But that’s not all: Another important difference is that babies spend a lot more time in REM than we do.

Whereas average adult spends only 20% of total sleep time in REM, for newborns the percentage is higher than 50% (Grigg-Damberger 2017; Wielek et al 2019). Time spent in REM declines as babies get older, but the change my come slowly. For some 9-month-old babies, REM still makes up 50% of their total sleep hours (Montemitro et al 2008).

And it’s crucial to understand the tricky appearence of baby sleep. During REM and transitional sleep, babies may behave in ways that look and sound like waking.

Adults experience sleep paralysis during REM, but this isn’t true for young infants, especially not for babies under the age of 3 months. Instead, these infants may twitch, wiggle, stretch, and thrash. They may frown or smile, or launch into a burst of sucking movements. They may vocalize too (Grigg-Damberger 2017; Barbeau and Weiss 2017).

So babies in REM can appear deceptively awake, and the same can be said for babies in transitional sleep. During transitional sleep, newborns become more likely to vocalize, and sometimes even open their eyes (Barbeau and Weiss 2017). 

It’s really only during “Quiet Sleep” that young babies present us with reliable cues that they are asleep. Aside from the occasional sigh, their breathing becomes slow and regular, and they scarcely move at all. But young babies spend only a minority of their time in quiet sleep — approximately 20 minutes per sleep cycle (Grigg-Damberger 2017).

This can lead the exhausted parent to make an understandable but unfortunate mistake: You misread your baby’s cues, and end up disrupting your infant’s sleep.

It happens innocently enough. You hear your baby whimper. You observe movement. You might even see that your baby’s eyes are open. So you bow to the inevitable, and swoop in to soothe him or her. You start talking, or you pick your baby up.

It seems like a good idea at the time. Isn’t it better to be proactive, to jump in before your baby has become really noisy or agitated? But your basic premise was faulty. Your baby wasn’t awake, but rather in REM or transitional sleep. Or perhaps what you mistook for waking was one of those brief arousals  — a fleeting moment of drowsy wakefulness that would quickly transitioned back into sleep if you’d left your baby alone.

Either way, you’ve intervened unnecessarily, and added a night waking to the schedule that might not otherwise have happened. And you may have denied your baby the experience of falling back to sleep on his or her own, without any fuss or distress.

If you make this mistake regularly,  you may be teaching your baby to turn brief arousals into full-blown waking sessions — and to expect lots of interaction with you.

To avoid this, be patient and observant before responding to your baby at night.

Get to know your baby’s quirks. And be aware that your social cues — especially the sound of your voice — can have particular powerful effect. Babies can awaken quickly when they hear us talk.

In fact, researchers note that babies “arouse more easily in response to their mother’s voice than to a smoke alarm” (Grigg-Damberger et al 2007).

Why do babies spend so much time sleeping light?

It might seem like Mother Nature made a terrible mistake. Wouldn’t it be better if our babies slept soundly and deeply all night? But REM may be important for a baby’s brain development (Siegel 2005). According to one theory, it could be a time for the brain to test its wiring — including the nerves that run to the skeletal muscles.

In addition, it’s likely that active sleep — and a tendency to awaken easily — helps protect babies from oxygen deprivation.

When a sleeping individual isn’t getting enough oxygen, it’s crucial to wake up immediately. Being slow to respond puts babies at higher risk for sudden infant death syndrome, or SIDS.

So there is a survival advantage to sleeping light, and that’s what REM sleep delivers.

Researchers have demonstrated this in experiments on sleeping infants. They subjected the babies to mild reductions in oxygen. Would the infants promptly awaken? Babies did arouse quickly — if they had been in REM sleep. But if the oxygen levels dropped while babies were in quiet sleep, the outcome was different. Babies aroused more slowly, or failed to awaken altogether (Parslow et al 2003; Richardson et al 2007).

It appears, then, that long bouts of quiet sleep could be hazardous, at least for infants young enough to be at risk for SIDS. For the first 6 months, sleeping relatively light — and being easily aroused — is a good thing. It makes babies safer. 

As a result, we must be thoughtful when we’re evaluating sleep advice. A given tactic isn’t automatically desirable because it results in babies sleeping more deeply or for longer stretches of time.

On the contrary, experts recommend some practices because they support more frequent arousals in young infants.

For example, babies who are breastfed tend to experience more frequent arousals than babies who are formula-fed. Researchers suspect this is one reason why breastfed infants have lower rates of SIDS (Horne et al 2004b; Franco et al 2000). You can read more about environmental risk factors for SIDS — and sleep practices to avoid — here.

So how much sleep do babies need?

This is a surprisingly difficult question to answer, especially for younger babies.

We know what international surveys tell us about typical baby sleep patterns. Among parents with babies under the age of 3 months, approximately 50% say their infants  sleep between 13-16 hours over the course of a 24 hour day (Iglowstein et al 2003; Bruni; Netsi et al 2017; Kohyama et al 2011).  

This might suggest that 13-16 hours is what most young babies need. But the surveys have limitations.

First, they are based on parental reports, which can be inaccurate. When scientists measure sleep objectively, they find disparities between parental perceptions and reality. Parents tend to overestimate total sleep duration, and underestimate the frequency of night wakings (Goodlin-Jones et al 2001; Galland et al 2016).

Second, even if we could be certain about the numbers, the numbers wouldn’t constitute proof about what babies need. Maybe the babies in these surveys aren’t getting enough sleep. Or maybe they’re getting too much.

What’s needed is research that addresses the health consequences of sleep, and unfortunately such research is in short supply (Paruthi et al 2016).

Citing this lack of evidence, the American Academy of Sleep Medicine has declined to issue any specific recommendations about sleep duration for babies under the age of 4 months (Paruthi et al 2016).

For older babies (4-12 months), the Academy notes that some studies have found links between emotional or behavioral problems and short sleep. On this basis, the Academy advises that 4- to 12-month-old babies are at a lower risk for problems if they get between 12-16 hours of sleep every 24 hours (Paruthi et al 2016). For more information, see my page about baby sleep requirements, as well as this Parenting Science sleep chart.

What about sleeping through the night? When do babies begin sleeping in long, uninterrupted nighttime bouts?

Understandably, parents want their babies to “sleep through the night.” But, as we’ve already noted, nobody truly sleeps through the night — not in the sense of remaining in a constant sleep state for hours on end.

Instead, what’s normal — both for babies and adults — is to experience many partial arousals throughout the night, and to occasionally wake up, if only very briefly.

Researchers have captured this in video recordings: Babies under the age of 12 months awaken, on average, 3-4 times a night (Goodlin-Jones et al 2001).

So it isn’t realistic to expect your baby to stop awakening at night. Nor would that be a good idea. As we’ve seen, arousals serve an important function.

Instead, a more reasonable goal is for your baby to settle down at night for at least 5 hours at a stretch. When your baby experiences an arousal, he or she quickly falls back to sleep — without your assistance.

That’s what’s really going on when parents say their babies sleep for long periods of time. The infants are experiencing normal arousals and night wakings, but their parents aren’t aware of these interruptions. Babies are staying quiet, and returning to sleep on their own.

So when does this happen? At what age do babies keep quiet for at least 5 hours? Between, say, midnight and 5am?

The answer is that it varies.

Some babies achieve this milestone at two months postpartum. But most babies don’t get there until 4-6 months, or even later.

We can see this pattern in a study that tracked 75 American infants over time. Jacqueline Henderson and her colleagues asked their parents to keep sleep diaries — 6 days per month — throughout the first 12 months postpartum.

Most parents didn’t record long stretches of sleep, not when their babies were very young. At two months, only 8% of parents reported that their babies were sleeping uninterrupted between the hours of midnight and 5am.

But by 4 months, approximately 50% of parents made this claim. And by 5-6 months, the majority of parents — about 70% — said their babies were sleeping without any perceived interruptions during these potentially crucial hours. At 12 months, the percentage had increased to 84% (Henderson et al 2010).

Factors that can affect the timeline — or temporarily shake things up

Baby sleep patterns are shaped by a mix of genetic and environmental factors. For instance, in two studies of 6-month old babies, almost half the individual variation in nighttime sleep duration could be explained by genetic factors (Dionne et al 2011; Touchette et al 2013).

By contrast, individual differences in the trajectory of napping — whether babies decreased napping from 6 months onward — were almost entirely explained by environmental factors, like whether parents promote or discourage napping.

How do genes influence baby sleep patterns?

One route is by shaping infant temperament. If your baby tends to be less adaptable or more irritable, it’s going to be harder to quiet him or her down, and studies confirm that such babies tend to experience more sleep difficulties (Weissbluth and Liu 1983; Van Tassel 1985; De Marcas et al 2015; Morales-Muñoz et al 2020).

Genes may also influence sleep in other ways. For instance, studies of adults indicate that certain genes can affect brain activity during sleep stages — leading some people to sleep more efficiently than others (Shi et al 2017). And recent research confirms that genes for chronotype can affect baby sleep patterns. In one study, infants with genetic profiles associated with eveningness (so-called “night owls”) tend to fall asleep later at night (Morales-Muñoz et al 2021).

But regardless of your child’s genetics, it’s clear that parenting has an impact on infant sleep patterns.

As noted above, parents can shape naps, influence the development of circadian rhythms, and help babies learn to resettle themselves after waking at night (as we’ve seen above). And it’s likely that parenting practices — which differ from culture to culture — can even affect how much total sleep an infant gets.

For example, consider differences between babies living in the Netherlands, and babies living in the United States (van Schaik et al 2021; Super et al 2020).

In the Netherlands, parents adopt a parenting philosophy that emphasizes “rest, regularity, and cleanliness.” They believe in organizing daily life so that’s predictable and calm, with regular, daytime opportunities for sleep.

By contrast, parents in the United States tend to favor high levels of infant stimulation during the day. They initiate exciting social interactions. They encourage their infants to play with interesting toys. And they take a more spontaneous, less regulated approach to sleeping schedules.

These are pretty big cultural differences in parenting, and they are associated with markedly different sleep patterns. Babies in the Netherlands get more sleep each day (more than 90 minutes, on average) because they take more naps. In addition, these Dutch babies spend more time in Quiet Sleep — almost two hours more than is typical of American infants (Super et al 2021).

Finally, individual infants will sometimes experience “sleep regressions” — temporary setbacks in sleep-related behavior.

There isn’t any universal timing for these setbacks. They vary from baby to baby, depending on what’s going on in an infant’s daily life. For instance, motor milestones — like learning to crawl, learning to stand, and learning to walk — can disrupt a baby’s sleep habits (Atun-Einy Scher 2016; Scher and Cohen 2015). But different children reach these milestones at somewhat different ages, and they respond in individualistic ways.

What if your baby isn’t a “good sleeper”? Is there something you can do to improve baby sleep patterns?

We’ve already seen that you can help your baby develop mature circadian rhythms. If your baby isn’t sleeping well at night, make sure your baby is getting the right environmental cues — bright light during the day, darkness before bedtime, and a boring, peaceful nighttime atmosphere. This will help your baby get sleepy at the right time — and spend more time sleeping at night.

We’ve also seen that there are mistakes parents can make during the night — mistakes that can prevent babies from learning to fall back to sleep on their own. If you can resist the urge to interact with a baby who seems to be waking — and wait to make sure the baby isn’t really asleep, or about to go back to sleep without your assistance — you’ll help your baby learn to sleep for longer periods.

In addition, you can troubleshoot for common sleep problems. Check out my overview of common infant sleep problems and what to do about them, as well my Parenting Science article about illnesses and physical ailments that can disrupt baby sleep patterns.

Finally, for more evidence-based information about parenting tactics that support infant sleep, see my article, “Finding the right infant sleep aid.” And keep these tips in mind:

1. Remember that soothing, supportive, emotional communication is the key to getting babies settled.

Whether your baby shares a room with you, or sleeps elsewhere, you can make it a point reassure and calm your baby before bedtime. Being sensitive and responsive to your baby’s moods is called “emotional availability,” and studies show that it has an important impact on the way infants sleep. When parents show emotional availability at bedtime, babies wind down more easily, and they experience fewer sleep problems (Teti et al 2010; Jian and Teti 2015).

2. If your baby wakes up because he or she is hungry, learn about “dream feeding.”

There’s reason to think that your baby might sleep a bit longer if you can get him or her to “tank up” on milk immediately before bedtime. Read more about it in my article, “Dream-feeding: An evidence-based guide to helping babies sleep longer.”

3. If you baby doesn’t seem to be sleepy at bedtime, don’t try to force it.

Getting pushy doesn’t make babies any sleepier. If anything, it makes them more excitable. And you don’t want your baby to associate bedtime with conflict. That can be a difficult lesson to unlearn!

So instead, try the technique known as “positive routines and faded bedtime,” which you can read about here. It’s a method for resetting your infant’s inner clock, and overcoming bedtime resistance by establishing a regular, soothing bedtime routine.

4. Are you concerned that your baby isn’t getting enough sleep?

Overall, researchers suspect that babies are pretty good at regulating their sleep requirements. As long as they are given the opportunities, they probably sleep as needed. But if you want to learn more, see my article “Baby sleep deprivation.” In it, I review the common signs that an infant is suffering from insufficient sleep, and talk about problems associated with chronic sleep loss.

5. If your baby seems to cry inconsolably, or seems otherwise distressed, discuss this with your doctor.

It’s not clear if excessive, inconsolable crying disrupts baby sleep patterns, but it definitely stresses out parents. And when parents are stressed out, they suffer more sleep problems. Read more about inconsolable crying and its possible causes in this Parenting Science article.

6. Watch out for those late naps.

Naps are good for babies. As I explain elsewhere, they help babies learn! But poorly-timed naps can cause trouble. A long snooze in the late afternoon can delay drowsiness for hours, wrecking havoc with your baby’s bedtime.

7. Take care of yourself.

Parents sometimes focus on how much total sleep they’ve managed to cobble together. But research suggests that sleep quality matters as least as much as sleep quantity. In my article, “Interrupted sleep: What are the effects, and how can we cope?” I talk about the detrimental impact of night wakings, and how we can apply the lessons of sleep science to protect our health and well-being.

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Written content last modified 9/2023; new image added 3/2022

image of father holding sleepy infant by monkeybusinessimages / istock

Portions of the text appeared in older versions of this article, including one entitled “Baby sleep patterns: A guide for the science minded,” last published in 2014, and a more recent version published in 2018.