1.Newborns and Infants
They spend most of their time — about 70% — asleep. Experts think all that shut-eye is what helps them learn and grow. Newborns tend to snooze for 2 to 4 hours at a time, up to 16 to 18 hours a day. They also have more active sleep than adults. That means they start out in rapid eye movement (REM) sleep instead of non-rapid eye movement (NREM) sleep. They might twitch a lot, too. That’s because the part of their brain that stops them from moving during dreams is still forming.
2.3 to 12 Months Old
A baby’s circadian rhythm, or wake and sleep cycle, falls into a more regular pattern when they’re a few months old. Their bodies start to make hormones like melatonin and cortisol. These chemicals tell them to stay awake during the day and sleep at night. Babies may start to conk out for long stretches — 6 hours or more — anywhere between 6 months to 12 months old. They start to spend more time in deep sleep. And their body temperature starts to follow a 24-hour cycle.
