Circadian Rhythm: what is it & how it can help your little one's sleep!

Part of what makes our little ones - and us! - get to sleep is something called the Circadian Rhythm. Simply put, it is our body's internal clock. Based on the time of day, it is how your body signals when it is time to do something, like wakeup, eat, and...sleep! Understanding how it works, we can use it to our advantage with our little ones! So...just how can we do that? Read below to find out.

What is the Circadian Rhythm?

As mentioned above, the circadian rhythm is your body's internal clock, which takes charge of the timing of what happens in your body. Sleep, producing hormones, meal times, and even when to go to the bathroom are all influenced by the circadian rhythm. Even though this is an extremely complex process, simply put - our bodies know what to do and when based on light and dark exposure as well as external temperature which triggers hormone production.

We aren't born with an established circadian rhythm. So when does this happen and how?

Developing Circadian Rhythm

Infants are not able to regulate their day-night rhythm and they also do not produce their own melatonin. Melatonin is the hormone released in the brain in dim-lighting and cooler temperatures and creates a feeling of sleepiness. For this reason, infants tend to mix their days and nights because they do not have the ability yet to regulate their sleep-wake rhythmicity which comes from the release of hormones that they are not producing yet.

The day and night confusion also comes from the fact that infants tend to have really high sleep needs after birth - 2/3rds of 24 hours could be spent sleeping - and their sleep-wake cycle is mostly regulated in the beginning by feeding rather than light exposure. This also explains the lack of a napping pattern.

Around 12 weeks of age, infants will start to produce melatonin. Prior to this moment, infants who are breastfed will be exposed to a precursor to melatonin (tryptophan) via their mother's milk.

The circadian rhythm begins to consolidate your newborn’s sleep at night and wakefulness during the day at this point. You could start to see a regular bedtime emerge at around 3 months. By 6 months, the circadian rhythm establishes a solid sleep-wake pattern throughout the day.

Why is this important?

It is important to understand the changes that your little one is going through to better help them and be able to prepare them for what is to come. If you know, that around 3 months of age, they will start to produce melatonin on their own for example, there are things you can do to help establish the circadian rhythm and make it work for you instead of working against it. Explanation?!

How can we use the Circadian Rhythm to our advantage?

We know that the circadian rhythm functions at its best when we stick to consistent timings throughout the day - eating at the same time, waking up at the same time, and going to sleep at the same time - and our body will respond accordingly by producing hormones to help us manage those processes or actions.

Being so, we can use the circadian rhythm to our advantage by avoiding varying bedtimes and waketimes. Sticking to each - within 30 minutes - each day can really help establish their rhythm and make waking and sleeping a much simpler process. There are some exceptions to this rule but only in special circumstances, like when they are extremely tired for example.

Because it is controlled by exposure to light and dark and the temperature, your child’s room environment is extremely important during times of sleep. Let's talk first about light and dark.

To help your little one start to produce melatonin and get ready for sleep, you can dim the lights about 1-2 hours before bedtime. This is also a good timeframe to avoid using electronics. All electronics tend to have a blue/white light which inhibits the production of melatonin. For adults that need to use their devices in the evening, I highly suggest turning on your night mode which makes the screen a warm color - the warmer the better! Once you go into your child's sleep space, check to be sure there aren't any blue lights on electronics that could influence melatonin production as well. If you do need a nightlight, make sure it is a red one! One of the key things is to make sure that their sleep space stays the same all night until the wake in the morning. Any change in light could cause your little one's body to begin producing cortisol and wake them up!

Now let's talk about temperature.

Our bodies need to be cool to sleep. Our circadian rhythm naturally lowers our body temperature to prepare for sleep. The optimal room temperature is between 18-20°c or 65°F. So again, lowering the temperature in the house around 1-2 hours before bedtime will also help promote sleep. Therefore it is important to consider when we have bathtime, do exercise, or even how warm our sleep space is. Giving ample time for our bodies to cool off is very important! No one can sleep when we are too hot. This goes the same for PJs! If they are waking up sweaty in the middle of the night, you know the room is either too hot or their clothing is too warm.

It is also incredibly important to try and find your child's natural rhythm with sleep needs and timing. If you miss your child's natural time to fall asleep, the circadian rhythm promotes a period of wakefulness (Wake Maintenance Zone) again before dipping again to promote sleep. This wakefulness could last anywhere from 40 minutes to 3 hours with peaks of wakefulness and dips of sleepiness until falling asleep.

Would you like more information on how you can use the circadian rhythm to your advantage or just need some advice on setting the right timings for your little one? I am always happy to talk and brainstorm ways to help your little one get the sleep they need. Feel free to send me an email at or book here for a free call!


Keijzer, H.; Smits, M.; Duffy, J.; Curfs, L. (2013) Why the dim light melatonin onset (DLMO) should be measured before treatment of patients with circadian rhythm sleep disorders. Sleep Medicine Reviews 18: 333-339

Chu CJ, Leahy J, Pathmanathan J, Kramer MA, Cash SS. The maturation of cortical sleep rhythms and networks over early development. Clin Neurophysiol. 2014;125(7):1360-1370. doi:10.1016/j.clinph.2013.11.028

Acuña-Castroviejo D, Escames G, Venegas C, Díaz-Casado ME, Lima-Cabello E, López LC, Rosales-Corral S, Tan DX, Reiter RJ. (2014) Extrapineal melatonin: sources, regulation, and potential functions. Cell Mol Life Sci. Aug;71(16):2997-3025.

Sleep - Circadian Rhythm by Dr. Alex Dimitriu -

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