How are Baby Sleep Cycles Different from an Adult’s?

Infant sleep is always a hot topic, especially for new parents who are trying to figure out how to get enough rest — both for themselves and for their baby. Understanding how baby sleep cycles work can help parents make sure that babies are getting the right amount of sleep, are adjusting to their baby’s changing sleep needs over the first year, and are setting their baby up for a lifetime of healthy sleep.

What Makes Baby Sleep Cycles Different?

To understand baby sleep patterns, it’s important to understand how an adult’s sleep cycle works. During the night, typical adults move through four sleep stagesVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View source: one stage with rapid eye movement (REM) and three with non-rapid eye movement (NREM Stages 1, 2, and 3).

• NREM Stage 1: Sometimes referred to as “quiet wakefulness,” this is an early stage of sleep where you can be easily woken by small noises or movements.
• NREM Stage 2: Your body temperature drops, and your muscles relax as you fall more deeply asleep. You are more difficult to wake even if there is light, sound, or movement.
• NREM Stage 3: During “deep sleep,” your body is relaxed, and you are very difficult to wake. This is an important restorative sleep phase where memories are consolidated, and the body repairs itself.
• REM Sleep: Called REM because of the way eyes move rapidly back and forth (rapid eye movements), this is the part of sleep where you dream.

During the night, adults move through these phases in cycles, from light sleep to deep sleep and back, multiple times. One sleep cycle takes around 90 minutesVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View source to two hours, so three or four sleep cycles will occur in a single night. Adults spend around a quarter of their night in REM sleep. Adults also have several light awakenings throughout the night during light sleep, described as brief moments where the brain “checks in” to make sure that nothing is amiss and there is no danger before settling down into sleep again.

Newborns, meanwhile, don’t follow the same four sleep stages. Instead, they move back and forth between quiet sleep and active sleep. During quiet sleep, their bodies are limp and relaxed, and they can be difficult to wake. During active sleep, their sleep is lighter; they may grunt or move their arms and legs, and waking them up is much easier.

A baby’s sleep cycle lasts for about 40-50 minutes. It is common for healthy newbornsVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View source to wake after just one or two sleep cycles, especially in those early days. Newborns have very small stomachs and need to eat about every three hours. Unfortunately, parents of newborns will have a few weeks when they are up every few hours around the clock.

Why Do Newborns Spend So Much Time in REM Sleep?

If adults spend about 25% of their night in REM or rapid eye movement sleep, why do babies spend almost 50% of their sleep in a dreaming state?

REM sleep serves similar functions in both children and adults; it helps consolidate memories and lets your brain “file” them to make them easier to recall later. Adults tend to have fairly routine days with many activities we can do on autopilot; our brains don’t need to make a lot of memories and store them as carefully.

Babies, meanwhile, are living in a brand new world and have constant new experiences that their brains have to catalog, understand, and file away for later use. Then, they enter a deeper NREM sleep that lets their bodies grow and further develop what they have learned while they are awake. Creating good sleep habits early can help your baby throughout the rest of their life.

How Much Sleep do Babies Need Overall?

The amount of sleepVerified Source Centers for Disease Control and Prevention (CDC)The United States’ health protection agency that defends against dangers to health and safety.View source a baby needs changes as they age, and every baby is different. For full-term infants, however, a rough guideline is:

• Newborns sleep between 16-20 hours a day in their first six weeks, usually in 2-4 hour chunks that are spread evenly throughout the day
• From 3 months to 6 months of age, babies may sleep up to 14 hours a day with one long sleep at night and 3 naps roughly 2 hours each. Some babies will sleep 8 hours at night by 6 months old without waking to feed.
• From 6 months to one year old, babies sleep the same number of hours but tend to shift their sleep from naps to nighttime sleep. A 1-year-old may only take 2 naps; naps overall tend to be from an hour to two hours long.

SEE ALSO: How Much Sleep Do Kids Really Need?

Why Don’t Babies Sleep Through the Night?

Circadian rhythm is the 24-hour cycle that governs many aspects of our lives, including sleep. It is affected by hormones, genetics, and light exposure. When born, infants have a very primitive circadian rhythmVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View source; light exposure and the parents’ routine help that rhythm develop into a more mature day and night cycle, which often shows a more mature pattern around two monthsVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View source.

Even as their circadian rhythm develops, however, babies continue to follow a newborn sleep pattern until they are around three months old or weigh more than 12 pounds. When they hit this benchmark, babies are usually big enough to eat bigger meals and go longer without food. Their sleep starts to “chunk” up, meaning that they can link more than one sleep cycle together; they may sleep as much as 6-8 hours a night.

They also tend to start following sleep patterns that are more similar to adult sleep cycles. They don’t immediately fall into a REM sleep stage, spend gradually less time in REM sleep, and have a more adult transition from light sleep to deep sleep and back. All of this means that parents can get some much needed rest.

Why Does “Four-Month Sleep Regression” Happen?

Babies are famous, however, for the “four-month sleep regression.” Around four months old, many babies who have been “great sleepers” begin to struggle to sleep and may cry at bedtime. This may occur because their bodies are moving into a lighter NREM phaseVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View source between sleep cycles. Just like adults, they may have that brief moment of wakefulness where their brain checks to make sure everything is safe.

Unlike adults, however, more things are unfamiliar, so it’s easier for the brain to be aroused. The baby also may simply not know how to fall back to sleep from that light awakening yet. Babies respond to this upsetting situation in the one way they know how — they start to cry. With help from adults in the form of gentle feeding, shushing, and settling back to sleep, babies learn how to sleep longer by staying asleep through the lighter sleep stages and by putting themselves back to sleep if they do awaken.

Big sleep changes can also occur when babies are learning to creep, crawl, stand, and walk. When infants have those brief awakenings, since they can move around, they may decide to check things out by standing in their cribs or crawling around to get a better view. This can make them too alert to fall back asleep easily, leading to asking their parents for help — by crying.

How Can Parents Help Babies Get Enough Sleep?

New parents often feel like they struggle to make sure their baby sleeps enough or worry that the baby should sleep longer. Their worries can be even more stressful since science often reminds them that establishing good sleep patternsVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View source early on has benefits for the rest of someone’s life. Happily, there are a few ideas that can make it a little easier for the baby to get the amount of sleep they need.

Meet the Baby’s Needs Before Sleep

Before you try and get your baby to sleep, meet as many of their needs as possible:

• Make sure they’re in a clean diaper, they’re fed, and they have calmed down from activity during the day.
• Help them to snuggle in and get ready for some sleep.
• Bring them to a quiet place where the low light will encourage their bodies to relax.

You want to avoid having your infant wake early because they’re hungry or have a dirty diaper, especially during the newborn period.

Newborns also tend to have a quiet, attentive period as soon as they’re awake. Feeding them during this time is ideal because they are calm, alert and most hungry. Since they get tired quickly, waiting may lead to them falling asleep while eating, which can mean they sleep less since they take less food.

Support the Developing Circadian Rhythm

Infants are building their circadian rhythmVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View source as they grow. While some pieces of circadian rhythm are genetic, environmental and behavioral elements can support a healthy pattern.

Many of the sleep tips for supporting healthy patterns in infants are true for adults as well:

• Get plenty of sunshine during the day
• Dim the lights in the evening, especially blue lights that can interrupt the body’s natural hormone cycle that encourages sleep
• Create a bedtime routine that encourages relaxation with low key, winding down activities like a bath, a favorite book, some soft cuddles time, and then finally laying down to sleep

At the same time, as newborns begin to be more awake during the day, encourage them to be active. Make eye contact, play with them, give them engaging toys, and make sure they get plenty of daylightVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View source. This helps their bodies learn that daytime is for being awake and active and nighttime is for resting.

As infants get older and begin to consolidate their daytime sleep into naps, having a shortened nap routine can also help create a good sleep pattern.

Trying to put a very active and awake baby straight to bed is going to be as ineffective as an adult trying to come from work and just lay down to get a full night’s sleep. Building in time to wind down for a nap is just as important as winding down for bedtime.

What to Do about Nighttime Wakings in Babies?

First, it’s important to remember that night waking is common in infants. Because they need to eat, because they wake up after a light sleep stage, or simply because the world is so interesting, a baby may wake up in the middle of the night and not be able to fall asleep again.

For parents, it’s important to keep any interactions at night very low-key and calm. Keep the lights dim, use a low voice, and try not to make much eye contact (eye contact is very arousing for infants). As soon as they’re ready to go to sleep, put them back in their crib and leave quietly.

When Can Babies Put Themselves Back to Sleep?

At some point in their development, most babies start to need less parental involvement to fall asleep. Parents can encourage this by following a regular routine and then, as their infant allows it, putting them into their crib before they’re all the way asleep.

This allows babies to start to learn to self-sootheVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View source, or fall asleep on their own. This skill can be particularly helpful with older babies who may naturally wake once or twice during the night, but be able to go fall back asleep without needing their parents’ help — meaning parents get to stay asleep.

“To ensure that your infant starts to sleep through the night when they are developmentally ready, allow them to fall asleep independently as often as possible from the very start,” says Dr. Vyas. “The more this is done, the less likelihood of sleep-related intervention and the higher the likelihood for them to have great sleep habits for their lifetime.”

Parents should also put their infants on their backsVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View source to sleep, make sure there isn’t anything soft in the crib, and avoid cosleeping.

How Much Sleep Does Your Baby Need?

If every baby is different, how do you know if your baby is getting enough sleep? Experts often suggest that you don’t compare your baby to others. Instead, look at how your baby is doing. Are they happy, playing, meeting their developmental milestones, and growing? Then your baby is probably getting as much sleep as they need.

If they seem grumpy and fussy, check on their sleep. You can:

• Keep a sleep diaryVerified Source National Library of Medicine (NIH)World’s largest medical library, making biomedical data and information more accessible.View source for your baby. This will help you gather objective information on how many hours of sleep a baby is getting over 24 hours. Remember that baby sleep is measured over 24 hours. If they’re taking two naps for 3 hours each during the day, for example, they won’t sleep as long during the night.
• Look for simple fixes. Are you giving a bath at night to help your baby sleep, but find it wakes them up? Shift bath time to a different point in the day. Are there very interesting toys right in their view from their crib? Move them to a different spot so your baby doesn’t wake up and get excited by their favorite thing. Remember that your bedtime routine has to work for you and your family, so while you can take suggestions from friends and family, it’s okay to individualize things.

If your baby isn’t getting enough sleep and simple changes don’t help, or if they seem to be getting enough hours of sleep, but still aren’t feeling well, it’s a good idea to check with a pediatrician just to make sure everything’s alright.