Why do we need to sleep every night?

Tonight, Na wanted to stay up late and keep playing with Cú Bông. “Sleep is such a waste of time,” she said.

The next morning, Na could not stop yawning and found it hard to concentrate. She wondered whether staying up late had anything to do with it.

The newborn baby next door, meanwhile, slept a great deal, day and night. Why does everyone need sleep — and why do some need so much more?

While we sleep, the body rests and gets ready for the next day. Enough sleep can help us fall ill less often, concentrate and remember.

Scientists think sleep may help the brain strengthen what we have learned.

Choose a wake-up time, then move the bedtime to see the time in between. That is time in bed, which is not the same as hours of actual sleep.

You might not know

Newborns aged 0–3 months are advised to sleep about 14–17 hours a day.
Adults are advised to sleep at least 7 hours a night.
People and many animals sleep or rest, each in their own way.

Sleep lets the body rest; enough of it can help us concentrate and remember. Children aged 6 to 12 are advised about 9 to 12 hours a day; adults, at least 7.

The chapter's sources

Everything this chapter tells you rests on at least two trustworthy sources, retold in the book's own words.

Why Do I Need to Sleep? (for Kids) — Nemours KidsHealth
About Sleep — U.S. Centers for Disease Control and Prevention
Healthy Sleep Habits: How Many Hours Does Your Child Need? — American Academy of Pediatrics, HealthyChildren.org
Brain Basics: Understanding Sleep — U.S. National Institute of Neurological Disorders and Stroke
How Much Sleep Do Babies and Kids Need? — Sleep Foundation (recommendations of the American Academy of Sleep Medicine)
How Many Hours of Sleep Do You Really Need? — National Sleep Foundation
How Much Sleep Is Enough? — U.S. National Heart, Lung, and Blood Institute
Do fish sleep? Here's what scientists have discovered so far — National Geographic