Baby Sleep Science and Sleep Training

July 24, 2022
 minutes read
Written by
Mandy Treeby
Chief Baby Sleep Consultant
Medically reviewed by
Elissa Gross, DO
Board Certified Pediatrician & Lactation Consultant

You may know that sleep coaching works with your baby’s natural, biological processes to teach your baby how to fall asleep faster and stay asleep longer, but what are those natural, biological processes? What’s happening inside and behind the scenes of your baby when they’re learning to and mastering sleep?


To help you make sense of it, here’s a brief rundown of the science of your baby’s sleep and how sleep coaching effectively and safely guides it.

And for more information on all things sleep-related – from why nap transitions are important to how to prevent early wakeups – check out the Smart Sleep Coach by Pampers™. Co-developed with pediatricians, sleep experts, and parents this easy-to-use app provides all the information, guidance, and, yes, relaxation you need to sleep coach quickly and effectively.

On Wake Windows and Sleepy Cues

First, the definitions of two sleep coaching terms that dovetail with the science… These will be referenced below and become very important when sleep training.

Wake Window: The amount of time your baby is awake between sleeps.

Sleepy Cues: Physical actions or behaviors exhibited by a tired baby who’s reaching the end of their wake window.

  • Yawning
  • Glazed eyes or avoiding eye contact
  • Rubbing their eyes.
  • Pulling their ears
  • Cranky

Watching for these is very important when sleep coaching because they tell you a wake window is closing. If you stay up much later, the wakeup hormones begin to circulate, leading to overtiredness.

Circadian Rhythm

One of the reasons to wait until 4 months to begin sleep coaching is because that’s when your baby’s circadian rhythm starts to mature.

The circadian rhythm is our internal clock that regulates our sleep, telling us when to wake and rest, over a 24-hour period. We all have them – babies, adults, even animals – and it’s largely controlled by daylight.

Newborns and very small babies are still developing this rhythm, which is why their sleep is very disorganized.

Once their circadian rhythm begins to solidify, between 12 and 16 weeks, you’ll notice your baby forms distinct wake windows and exhibits sleep cues when ready to rest. Sleep coaching works with those natural cues to shape your baby’s sleep, teaching them when it’s best to sleep and how to fall asleep on their own.

Hormonal Happenings

The circadian rhythm is regulated by four hormones that are released and suppressed over the course of a 24-hour cycle. Sleep coaching aligns nap and bedtimes with this natural cycle, so your baby falls asleep faster and stays asleep longer – and the Smart Sleep Coach makes it easy.

Here we define the hormones and then explain how they all interact, and how your sleep coaching aligns with these natural chemicals.

Adenosine: A “sleep drive hormone,” adenosine is slowly released as soon as your baby wakes up. Once the adenosine reaches a certain level, your baby’s body begins producing melatonin, which we explain below.

One thing to know, babies’ and toddlers’ adenosine builds up faster than an older child or adult. That’s why they nap so often – to “reset” their sleep tank .

It helps to think of it this way, when you wake up you’re like an inflated balloon that slowly deflates and is empty when it’s time for your next sleep.

Melatonin: Melatonin is a natural “sleepy” hormone that helps babies, and adults, fall asleep and rest well. As explained above, melatonin is released once adenosine reaches its upper level. This triggers them to get sleepy, which is when they exhibit sleepy cues like the ones mentioned above.

Cortisol: A “wake up” hormone released after adenosine is depleted. It signals the mind and body to rise and shine. If you miss your baby’s wake window, they’ll produce cortisol that wakes them up, leading to overtiredness.

Daylight and screens also stimulate cortisol production, which is why we recommend blackout curtains for your baby’s sleep space.

Serotonin: Another “wake up” hormone released when <name> is ready to wake up. As with cortisol, serotonin will be released if your baby stays up past their wake window. Also, like cortisol, it’s influenced by daylight – another reason why blackout curtains are so important when setting up your baby’s sleep space.

How the Hormones All Work:

When your baby wakes up, they produce adenosine. As adenosine builds up, your baby grows tired. This is called the homeostatic sleep drive.

When adenosine reaches a certain level, melatonin is released. This leads to drowsiness and sleepy cues. This is your golden opportunity to put your baby down to sleep.

By putting them down at the end of their natural wake window, we’re matching their natural biological rhythm which is the optimal sleep schedule.

Once your baby is asleep, the built-up adenosine recedes. When it hits its lowest level, it activates the production of cortisol and serotonin, the wake-up hormones.

Remember, daylight will also activate those hormones, which is why blackout curtains are so important in your baby’s sleep space.

Cortisol and serotonin will also be released if your baby stays up beyond their wake window, throwing them off sync, leading to overtiredness – and, trust me, that is the last thing you want in a baby.

How Sleep Coaching Works

Sleep Coaching takes a holistic approach to fine tune the three core sleep levers, the biological sleep rhythm, sleep environment and sleep behavior.

  1. Biological Sleep Rhythm : By working with your baby’s natural homeostatic cycle, we align nap and bedtimes to their sleepy waves. By catching your baby when they’re ready to sleep they will fall asleep faster and stay asleep longer.
  2. Sleep Environment : Where your baby sleeps is almost as important as when they sleep. Creating a sleep inducing environment for every sleep helps deliver positive sleep associations for your baby. Imagine yourself trying to sleep sitting up in a bright room? It would be much easier lying down in a dark room. The same goes for your baby.
  3. Sleep behavior: If you pat or rock or feed your baby to sleep, they will think they need that in order to fall asleep. In reality they can and will fall asleep without it, and since the act of falling asleep is a learned skill, you want to give your baby space and time to practice doing this themselves.

While They Were Sleeping:

Now that we’ve discussed the internal and biological functions behind sleep, let’s take a deeper dive into what’s happening inside your baby’s mind while they sleep.

You may have heard of REM sleep – “Rapid Eye Movement” sleep, but there’s also something called NREM sleep – non-REM sleep.

These two types of sleep work in tandem to help your baby rest and grow.

  • NREM sleep is a deep, restorative sleep that helps write to long-term memory
  • REM is a more active sleep that helps build learning and cognitive skills.

While your baby experiences both during a nighttime cycle, these sleeps’ concentrations or intensities are different at different times of day: There's more NREM sleep from 7pm-midnight and more REM from midnight on. That’s why early bedtimes matter - you want to ensure your baby is getting both types of sleep, REM and NREM.

NREM sleep appears earlier in the sleep cycle, which is why naps are also important.

An Infants’ Sleep Cycles

This is how an ideal night’s sleep cycle looks for infants.

Stage One: A transitionary period of non-REM sleep that’s lighter. During this stage your baby has just fallen asleep - maybe even still opening their eyes a bit - and it’s easier to wake them.

Stage Two: A slightly deeper though still light REM sleep during which your baby is easily awoken.

Stage Three: Though this is still REM sleep, it’s deeper than the previous two. During this time your baby’s harder to wake and motionless.

Stage Four: Deep non-REM sleep - when your baby is dreaming and possibly moving their arms, legs, or face. This stage usually happens in the first few hours of nighttime sleep before your baby returns to the earlier stages, which is why your baby may wake up earlier than usual from time to time. It’s rarer that your baby will reach stage 4 during a nap.

Now that you understand how sleep training works with your baby’s natural sleep powers, download the Smart Sleep Coach by Pampers™ to get step by step sleep coaching support from this game changing app!. In addition to bite-sized articles explaining even more about your baby’s sleep, the sleep tracking feature automatically updates your baby’s sleep schedule and its exclusive algorithm customizes sleep coaching approaches based on your baby’s unique sleep habits – all so your baby can sleep well today for a healthier, better rested tomorrow.

Step-by-Step Gentle Sleep Training

Few Parents Know, falling Asleep is a learned skill. Just like rolling, crawling, walking and talking – babies need help to master sleep.


Your Baby Can Be A Super Sleeper

Your personalized sleep plan is a few clicks away! Step-by-step sleep training with the Smat Sleep Coach app.


Your Baby Can Be A Super Sleeper

The Smart Sleep Coach app equips you with the tools and knowledge to get more Zzzz’s, turning you and your baby into a dream team. Start seeing results from day one.

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Your Baby Can Be A Super Sleeper

Your personalized sleep plan is a few clicks away! Step-by-step sleep training with the Smart Sleep Coach app.

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Studies show new parents can lose as much as two hours of sleep every night after their baby comes!

“Thanks to the Smart Sleep Schedule, I’ve been able to follow my baby’s natural rhythm, and stick to the wake windows. This makes a huge difference in her ability to nap longer.”

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Studies show new parents can lose as much as two hours of sleep every night after their baby comes!

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Thanks to the Smart Sleep Schedule, I’ve been able to follow my baby’s natural rhythm, and stick to the wake windows. This makes a huge difference in her ability to nap longer.

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