Sleeping baby holding a teddy bear

What is Your Baby’s Circadian Rhythm

Published on June 2nd, 2021

Sleeping baby holding a teddy bear

Your new baby is a bundle of joy. A miraculous source of wonder. A piece of your heart, experiencing the outside world for the first time. She’s also your new alarm clock. And while she’s certainly the most adorable clock you’ve ever had, she can also be the most unpredictable. 

That’s because, in her first few months of life, your infant is still developing her circadian rhythm. Fortunately, by identifying your baby’s sleep chronotype, establishing consistent routines, and creating calming infant sleep environments, you can help synchronize her circadian rhythm to yours for a less alarming sleep schedule. 

What is a circadian rhythm?

Circadian rhythms are our bodies’ 24-hour internal clocks. They set the tempo for our daily routines, letting us know when it’s time to wake up, eat, and go to sleep. If you’ve ever tried to nab a few extra hours of shut-eye on a responsibility-free day, only to find yourself wide awake at your standard 6 AM rising time, you have your circadian rhythm to thank. 

This is because our circadian rhythms have developed to signal to our brains when to produce two powerful hormones (according to the time of day): 

  • We produce cortisol during the day 

Cortisol is the hormone responsible for stimulating wakefulness and keeping us alert. Cortisol is sometimes called the stress hormone because, in times where our brain detects a potential threat (like an unexpected email from the boss in our inbox), this is one of the chemicals the brain floods our body with to keep us ready for fight or flight. Day-to-day, our body uses just enough cortisol to keep us alert and awake. 

  • We produce melatonin, the hormone responsible for drowsiness, at night

Darkness triggers our brains to go into melatonin mode, soothing our bodies into slumber. When the light receptors in our eyes perceive the blue light of sunshine, our bodies stop producing this melatonin, signaling it’s time to wake. 

We aren’t born with circadian rhythms. In fact, when babies are nestled in the snuggly darkness of Mom’s womb, their sleep and wake schedules aren’t determined by morning and night like they are for adults. Instead, babies in the womb tend to follow Mom’s schedule.

Sleeping and Waking in the Womb: A Baby’s Circadian Rhythm During Pregnancy 

When sleep and wake hormones flow through Mom, they travel through the placenta and affect the infant. That means when Mom is awake and active, her baby typically is too, and when Mom is starting to doze off into dreamland, her baby will likely follow close behind. The baby’s sleep patterns aren’t reacting to light or darkness while he’s snug in the womb. He’s reacting to Mom’s hormones, so his growing little brain doesn’t associate active time with daytime or sleep time with night time (yet). 

When the baby is born, and he’s no longer receiving hormones from Mom, he begins to establish his own circadian rhythm. 

How is circadian rhythm developed? Unlike musical rhythms (which are developed by spontaneous dance parties in the kitchen with Mom), circadian rhythms are strongly influenced by three factors: light exposure, sleep chronotype, and age. 

Rise and Shine: How Light Affects Circadian Rhythms 

When light enters our eyes, it’s detected by the retina—a thin layer of tissue along the back of the eyeball that contains millions of light-sensitive cells. The retina then sends this information through the retinohypothalamic tract to the suprachiasmatic nucleus—the part of your brain that holds your internal clock.  

When this clock detects light, its alarm goes off, alerting the rest of your brain that it’s time to wake up. Rather than hitting the snooze button, your body hits the pause button on melatonin production and brews a fresh cup of cortisol to start the morning. 

Over time, your circadian rhythm learns to anticipate your morning cortisol levels increase and melatonin decrease. This explains why even if you cocoon yourself in your comforter, your body will naturally wake up around the same time every morning.

Even with sufficient exposure to light during the day, your baby’s production of cortisol won’t begin to regulate until she’s about eight weeks old, with consistent melatonin production following close behind at around nine weeks. This is probably one of the reasons why your baby won’t sleep. It just takes time to develop the pattern of waking and sleeping. 

Until this time, you can clock your baby’s natural sleep tendencies to help her set the beat for her circadian rhythm. 

Early Birds & Night Owls: How Sleep Chronotype Affects Circadian Rhythms 

Sleep chronotype refers to an individual’s genetic predisposition to sleep during certain times of the day. To put it in more baby-friendly terms, it’s whether your little one is an early bird or a night owl. 

That’s right! This is a genetic trait, and it affects the baby’s sleep cycle just as much as it affects adults.

  • Night owls are naturally inclined to stay up later and therefore wake up later.
  • Early birds like to wake up early (to get the worm, of course) and prefer an earlier bedtime.  

By understanding your baby’s chronotype, you can establish a healthy sleep schedule that complements his natural tendencies and sleep cycle. This not only encourages the development of your baby’s circadian rhythm but it also makes morning wake-ups and evening bedtimes less of a feather-ruffling situation. 

Sleeping Like a Baby: How Age Affects Circadian Rhythms 

If you’re a parent to a newborn, you may be thinking, Awake before the sun? Wild in the evenings? My baby exhibits all of the chronotypes! 

You don’t actually have a zoological phenomenon on your hands. Because newborns are still learning the difference between night and day outside of Mom’s dark womb, they naturally showcase more sporadic sleep wake cycle schedules. 

Newborns also have a lot of growing to do. In fact, during your baby’s first three months outside of the womb, her brain continues to grow 1% every day. Not only does this growth allow her to remember all of the day’s new discoveries, but it also encourages her ability to learn: 

  • Language
  • Attention 
  • Impulse control 

And your baby’s brain isn’t the only part of her that’s growing. During deep sleep, the growth hormone is secreted, resulting in further bone and muscle development. It explains why your newborn is hard at work, snoozing away for 16-18 hours a day (if only grown-ups could develop muscle this way!).

Of course, these 16-18 hours of sleep don’t happen all at once. Your alarm clock, er… your baby will wake up every 2-3 hours to have a post-sleep snack session. This helps ensure your baby’s growing body receives all the nutrients it needs, regardless of the time of day. To help keep nighttime feedings from delaying the development of your baby’s circadian rhythm, we suggest maintaining a dark, soothing environment for your baby’s midnight snack (just not so soothing that you fall asleep yourself).

How to Help Develop Your Baby’s Circadian Rhythm 

Although a baby’s circadian rhythm will need time to develop, there are (baby) steps you can take to help move the process along. 

Establish a Consistent Sleep Schedule and Routine

We know your baby isn’t a stickler for scheduling. Still, by creating morning and evening routines, you help lay the groundwork for your baby’s circadian rhythm (because if there’s anything a circadian rhythm loves, it’s a consistent schedule). Doing this can also help you be aware and more easily manage baby sleep regression

To start, determine a morning wake-up time and a nightly bedtime. You can factor in your child’s sleep latency—the average time it takes for him to fall asleep—to calculate the best time for your child to be in bed, trying to fall asleep. From there, work backward to create the ideal newborn sleep schedule. By sticking to these times every day, you act as your baby’s circadian rhythm.

You can also create a pre-bedtime routine that will further signal to your baby (and his developing circadian rhythm) when it’s time to start winding down. Plus, a nightly routine allows for fantastic one-on-one bonding time for you and your little one. 

Consider incorporating any (or all!) of the following into your pre-bedtime ritual:

  • Relax baby with a warm bath 
  • Read a story together 
  • Sing your favorite lullaby 
  • Play quiet, soothing music
  • Rock your baby  
  • Massage your baby gently (those growing muscles need it!)

Keep in mind: the goal is for your baby to become drowsy in your arms, not to fall asleep in them. Otherwise, you run the risk of training your baby to only sleep in your arms. As sweet as that image is, your arms (and you) deserve a little rest, too! As soon as you see those eyelids start to flutter, gently place your little one in the crib.

Set the Mood for Sleep 

Work with your baby’s developing brain to help her set her own internal clock.

  • Play in the sunlight, sleep in the dark

Because light triggers your baby’s brain to stay awake, you can help her associate light with wakefulness by keeping playtime in well-lit areas. When it’s time for sleep (even for daytime sleep), make sure to keep your little one in a dark room. This will encourage melatonin production and strengthen that night-time equals sleepytime connection.

  • Keep midnight snacks dark

If your baby wakes up in the middle of the night and needs a midnight snack or a fresh diaper, maintain a dark environment. Don’t worry, you’ll become a pro at the dark, one-handed diaper change. Otherwise, too much light may jumpstart your baby’s brain into thinking it’s time to be alert and start a new day of adventure.

  • Minimize distractions before bed

After a dramatic Netflix binge-a-thon, heated board game, or animated discussion about your favorite book series, do you feel calm, soothed, and ready to snooze? Probably not. The same goes for your little one. Keep the pre-bedtime activities soothing, so your little one can wind down.

  • Learn more about your baby’s unique sleep traits

Did you know that genetics can impact your baby’s sleep habits? Discovering more about your baby’s natural sleep traits as predicted by genetics can give you the insight you need to set her circadian rhythm more efficiently. And you can do that easily with SneakPeek Early Traits DNA Test. 

Help Your Baby Rock Her Circadian Rhythm with SneakPeek Traits 

Whether you’ve got a fledgling night owl or a baby early bird on your hands, a good night’s rest can make all the difference in your child’s day and development. With a little help from SneakPeek Traits, you can learn your child’s unique sleep needs as predicted by genetics, including:

  • Sleep latency
  • Sleep efficiency
  • Sleep duration
  • Chronotype

Each report comes with insight custom to your child’s individual genetic traits, as well as handy guides to help you create a nourishing baby sleep schedule for your little one. Don’t snooze on your baby’s sleep health—learn more with SneakPeek Traits!


Sleep Advisor. Baby Sleep Facts for Parents.

US National Library of Medicine. PERSPECTIVE: The Long-Term Effects of Light Exposure on Establishment of Newborn Circadian Rhythm.

Healthline. Everything to Know About Your Circadian Rhythm

US National Library of Medicine. Melatonin the “light of night” in human biology and adolescent idiopathic scoliosis.

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SneakPeek aims to provide the most accurate and up-to-date information to help our readers make informed decisions regarding their health before, during, and after pregnancy. This article was written based upon trusted scientific research studies and/or articles. Credible information sources for this article are cited and hyperlinked.

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