Facts you need to know about your baby's sleep
Updated: Jun 23
Your little one’s sleep cycles differ greatly from your own
Children’s sleep cycles are quite different from adult sleep cycles. Up until age 2, they spend a lot more time in REM sleep (rapid eye movement, dream sleep) than NON-REM sleep (deep sleep). In the first 4 months, about 50% of their sleep is REM sleep (rapid eye movement, dream sleep) from which they can wake up quite easily. By age 2 children’s sleep is more similar to adult’s meaning REM sleep is now only 20-25%, so about 2 hours per night. Switching from one sleep cycle to the other makes your little one wake up a little bit (partial arousal) and if all is well they just roll over and go back to sleep. This is why if your baby falls asleep in your arms and then wakes up in their cot, instead of just rolling over and going back to sleep they will wake up fully wondering why they are no longer sleeping in your arms. This means that if your baby relies on any sleep crutches (feeding, rocking to sleep, etc.) they will cry out during those partial arousals as they need your help to get back to sleep. A baby without those sleep crutches and the ability to self-settle will not require your assistance during those arousals and thus not wake up crying.
Why a routine is so important for good sleep
Your baby’s circadian rhythm (their internal biological clock) is set by food, light, sleep, and social interaction. This is why it is important to expose your baby to lots of natural light when they first wake up in the morning to give them the cue that the day has started and then to make the room as dark as possible when it is time for sleep. Also during night wakings, there shouldn’t be any social interaction, just offer a quick feed and nappy change if necessary and settle your baby back to sleep. The circadian rhythm is controlled by the hormones cortisol (keeps us awake) and melatonin (makes us sleepy). The levels of these hormones fluctuate throughout the day which is why there are times where it is much easier to settle your baby to sleep. Melatonin peaks at midnight while Cortisol peaks at 6 am. This is the reason why having your baby sleep past 7 am is almost impossible as you would be fighting their internal clock. Dropping body temperature at night also helps babies settle to sleep and their body temperature is at their lowest at 3 am which can lead to night wakings if the child is cold. Working within the circadian rhythm will make changing your baby’s sleep habits a lot easier.
We all have certain sleep windows throughout the day which are controlled by our circadian rhythm. This means that if you put your baby down for a nap within those windows you will have a much easier time to settle them to sleep. This is when a routine comes in handy as establishing a routine for your child will teach them sleep cues and prepare them for naps and nighttime sleep. Keeping within those sleep windows means the child is producing melatonin which will help them fall asleep if you let your baby get overtired your child will produce cortisol instead which makes settling them for sleep very difficult.
Best times for your little one’s nap
From about 4 months of age, in line with your baby’s circadian rhythm, the best timings for your little one's naps are 9 am - 10 am, and 12 pm - 2 pm. This does not mean that your baby has to sleep from exactly 9 - 10 am and 12 pm - 2 pm but aim to start settling them for their nap within those times as you will be working within their biological clock, meaning settling them to sleep will be much easier. These biological nap windows are also why it is often quite difficult to settle a baby on a 3 nap schedule to sleep at 4 pm as this is not a biological nap time. This is why it is recommended to make that third nap an assisted nap and go for a nice walk in the pram, instead of trying to force a nap at home in the cot or bassinet.
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Ferber, R, 2006, Solve your child’s sleep problems, Fireside, USA
Walker, M, 2017, Why we sleep, Scribner, USA