This is how your child's body balances being awake and needing rest. The longer they stay awake, the more sleep pressure builds up, sending signals that it’s time to sleep, no matter the time. After being awake for about 15 hours, your child will feel more tired and have a stronger urge to sleep.

These are your child's natural body clocks, working on a 24-hour cycle to manage when they feel awake or sleepy. Circadian rhythms help the body adjust to environmental changes, like light and darkness. 

Circadian rhythms start to develop around 3 months of age, and you may notice this more when travelling to a different time zone or during daylight savings when your child’s body needs to adjust to different daylight hours. 

Ideally, circadian rhythms help your child feel alert in the morning and ready to sleep in the evening.