We spend about a third of our lives asleep. That’s a good thing. Sleep helps keep our brain, body, and immune system healthy. But from birth to older age, sleep patterns change throughout our life.

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.