This is how your child’s body balances being awake and needing rest. The longer they stay awake, the more sleep pressure builds up. This sends signals to their brain that it’s time to sleep- no matter what the clock says. After about 15 hours awake, most children will feel tired and have a strong urge to rest. 

These are your child’s natural body clocks, known as circadian rhythms. They work on a 24-hour cycle to help your child feel awake during the day and sleepy at night. Circadian rhythms also help their body adjust to changes in the environment, like light and darkness 

They usually start developing around 3 months of age. You might notice this more when you travel to a different time zone or during daylight savings. These rhythms help your child feel alert in the morning and ready for sleep in the evening. 

See Adjusting to daylight savings for more information on impacting children’s sleep.