Introduction
After working as a sleep consultant now for over 5 years with over 600 families in Vancouver and beyond, the number one fact that has been solidified for me over the years as I have refined my approach, is the importance of a healthy and optimized circadian rhythm in order to promote consolidated sleep for babies and toddlers. So many times, a client comes to me thinking that sleep training is simply applying a method and “letting a baby cry”. However, I can not overemphasize enough how important sleep pressure and the circadian rhythm is in order for a baby to catch on quickly, with as few tears as possible, to the sleep training process. I have seen numerous cases now that when we first optimize the daytime routine, sleep pressure and circadian rhythm for the sleep needs of an individual baby, sleep training can be achieved even with minimal tears, hold outs of night wakings.
One of the most common questions I get as a sleep consultant is, “Why do you recommend a bedtime around 7:30 pm?” or “Why does my baby keep waking up at 12 and 5:00 am?” Or “If I put my baby to bed later, will my baby sleep later”?
Many parents assume that sleep is simply about making a baby tired enough. If they’re awake long enough, they’ll sleep well, right?
In reality, so much of infant and toddler sleep comes back to biology and how deeply it connects to their internal clock and sleep needs. These sleep needs can greatly vary and when they are not accounted for, thats where no matter how much sleep training you do, you child might still wake at 12 or 5 a.m.
As I always say, half, if not more, of healthy sleep has very little to do with the sleep training method itself. It comes down to supporting your baby’s circadian rhythm and creating the right amount of sleep pressure. When these two systems are working together, sleep becomes much easier. When they’re working against each other, you can end up with bedtime battles, false starts, early morning wakings, frequent night wakings and short naps, even if your child is falling asleep independently. .
While every child is unique and can have sleep needs, babies and toddlers are surprisingly similar when it comes to their biological clock. Understanding how their circadian rhythm works can make a huge difference in supporting healthy, restorative sleep.
What Is the Circadian Rhythm?
The circadian rhythm is your baby’s internal 24-hour body clock. It regulates much more than just sleep. It helps control hormone production, body temperature, digestion, alertness and, of course, sleep.
Throughout the day, your baby’s body naturally releases different hormones at different times.
As evening approaches, melatonin begins to rise, preparing the body for sleep. In the morning, cortisol gradually increases, helping your baby wake up feeling alert and ready for the day.
This is why sleep isn’t just about how much sleep your baby gets. It’s also about when that sleep happens.
Every baby has a sweet spot for when this rise in cortisol and melatonin happens. And if the timing is off, it can really impact the quality of their sleep and their ability to fall and stay asleep easily.
Why Timing Matters
One of the biggest misconceptions I see is parents assuming that all hours of sleep are equal.
They’re not.
A bedtime of 7:30 pm is not biologically the same as a bedtime of 10:00 pm, even if your child sleeps the same number of total hours. Sleep before midnight is generally more restorative. However, too early of a bedtime can also backfire as melatonin is not quite high enough yet.
When bedtime aligns with your child’s circadian rhythm, falling asleep is easier, sleep tends to be deeper, and overnight sleep is often much more restorative.As well, a later bedtime doesn’t necessarily mean a later wake up time. Many babies and toddlers naturally wake up sometime between 6 and 7 a,m and a later bedtime can really lessen the overall hours of nighttime sleep.
This is one of the reasons I recommend an earlier bedtime for most babies and toddlers. It isn’t an arbitrary number—it’s working with their biology instead of against it.
The Ideal Circadian Rhythm for Most Babies and Toddlers
While there is always some flexibility depending on your child’s age and temperament, most babies and toddlers thrive on a schedule that looks something like this:
- Wake for the day around 6:00–7:00 am
- Bedtime around 7:30/8:00 pm
However, the amount of total wake time that child needs between these hours can greatly vary. High sleep need children need less while lower sleep need children need more in order to build the amount of sleep pressure to sleep well at night.
The timing of daytime naps can also impact a child’s ability to consolidate their night. Too much sleep later in the day can often cause wakings before midnight or early morning wakings.
What Happens Throughout the Night?
Many parents imagine that babies simply fall asleep and stay deeply asleep all night long.
In reality, sleep changes dramatically throughout the night and it’s why I can often guess when a child is waking based on their daytime schedule and number of wakings. This is due to sleep pressure getting lighter at these points and the child also doesn’t yet have the sleep skills or sleep pressure to bridge these independently.
The First Half of the Night
The first several hours after bedtime are when sleep pressure is at its highest.
This is when babies spend more time in deep, restorative sleep. Because sleep is naturally deeper, this is often the easiest part of the night.
This is also why bedtime usually isn’t where we see the most night wakings.
Around Midnight
As the night progresses, sleep naturally becomes lighter.
Many babies will briefly stir around midnight as they transition between sleep cycles. Babies who have build enough sleep pressure or have independent sleep skills often don’t fully wake and simply roll over, adjust their position and continue sleeping. However, midnight is an extremely common waking point for children who’s habits rely on their parents to bridge this part for them or if their daytime schedule is off.
Around 4:00–5:00 am
The early morning hours are another time when sleep naturally becomes much lighter.
This is one of the most common times for babies to wake because:
- Sleep pressure has decreased significantly.
- Melatonin levels are beginning to fall.
- Cortisol is gradually starting to rise in preparation for morning.
If sleep pressure isn’t quite high enough or the circadian rhythm isn’t well supported, this is often when we begin to see those frustrating early morning wakings.
This is also why babies who are overtired, undertired or relying heavily on sleep associations often struggle the most during this part of the night.
Sleep Pressure and Circadian Rhythm: They Work Together
I often explain to parents that healthy sleep is like putting together a puzzle.
One piece is sleep pressure and the circadian rhythm.
The other is the sleep habits.
Sleep pressure builds throughout the day while your baby is awake. The longer they’re awake (within age-appropriate limits) and the more it’s balanced with appropriate day sleep, the greater the drive to sleep.
The circadian rhythm determines when the body naturally wants to sleep.
Sleep habits determine how a child then falls and stays asleep as they come out of sleep cycles throughout the night and enter these lighter stages of sleep.
This is why I spend so much time looking at wake windows, naps, bedtime, morning wake time and the sleep environment before we ever talk about sleep training.
How to Support Your Baby’s Circadian Rhythm
Fortunately, there are several simple ways to support your baby’s biological clock.
Consistent Morning Wake Time
Morning wake time is one of the strongest anchors for the circadian rhythm.
Rather than sleeping in after a rough night, aim for a fairly consistent morning wake-up whenever possible.
Appropriate Wake Windows
Wake windows help ensure your baby builds enough sleep pressure throughout the day without becoming overtired or underwired. A general rule of thumb is to have shorter wake windows earlier in the day when sleep pressure is naturally higher and longer later in the day when it’s lower. This also helps for an efficient sleep onset and deeper first stretch of sleep.
Age-Appropriate Naps
Too much daytime sleep can reduce sleep pressure.
Too many naps can also not allow sleep pressure to build as usually wake windows are too short and a nap is happening too late in the day.
Tapering naps as the day goes is ideal (longer earlier in the day and shorter later).
An Ideal Bedtime
Contrary to what many parents expect, keeping a baby up later rarely results in them sleeping later the next morning. However, too early of a bedtime can also backfire as melatonin output is not yet high enough and a baby won’t be able to enter a deeper sleep as easily. Sometimes babies also treat early bedtime as a nap.
Keep Nights Dark
Darkness supports melatonin production and helps reinforce the message that nighttime is for sleeping.
Signs Your Baby’s Circadian Rhythm Is Well Supported
- Bedtime comes easily.
- Naps are more predictable.
- Night wakings are minimal.
- Morning wake-up is consistent.
- Your child generally seems well-rested.
Signs Your Baby May Need More Circadian Rhythm Support
- Bedtime battles
- False starts
- Frequent early morning wakings
- Short naps
- Split nights
- Difficulty settling before sleep
While these challenges can certainly have other causes, I almost always begin by looking at the child’s circadian rhythm and sleep pressure before making any changes.
The Bottom Line
One of the biggest things I’ve learned from working with hundreds of families is that healthy sleep isn’t simply about getting your baby tired.
It’s about working with their biology instead of against it.
When you support your baby’s circadian rhythm through consistent timing, appropriate sleep pressure, healthy routines and an age-appropriate schedule, sleep often becomes much easier.
Whether you’re sleep training or not, these foundations matter.
In fact, they’re often the reason why one child seems to learn healthy sleep habits quickly while another continues to struggle. I’ve had so many clients come to me who have already started sleep training and it’s not going well. It is almost always due to a sleep need/sleep pressure mismatch which doesn’t allow for an optimal circadian rhythm. Some babies even need very minimal formal sleep training once their schedule is optimized as it does the majority of the work. I especially see this when I work with a client already in the newborn stage where the circadian rhythm is just being established.
As I always tell parents, sleep training is only one piece of the puzzle. Supporting your baby’s natural circadian rhythm is one of the most powerful things you can do to help them become a confident, healthy sleeper.
If you feel like sleep training is the right fit for you and you are looking for some support, please check out more about my philosophy or book a free consultation with me.
Teresa Sedlmair is the founder of Little Trees Sleep Consulting in Vancouver, BC. She supports families with babies and toddlers in Vancouver, across the Lower Mainland and virtually abroad. She works closely with parents to navigate challenges like night wakings, short naps, co-sleeping and various other sleep associations such as rocking and feeding to sleep using practical, evidence based and responsive approaches. She is trusted by over 600 families and has an exclusive 5 star rating.
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