Every night of your life, something very mysterious happens to you. You lie down, close your eyes, and you FALL ASLEEP. OK, maybe that doesn’t sound very mysterious—after all, everybody sleeps, right? But sleep really is a mystery. Scientists don’t know a whole lot about it, but the things they do know are really cool. Read more to find out about the mysterious things that happen to YOU every night!
Why Do We Sleep?
Humans and animals both need sleep to live. People used to think that their brains turned themselves off when they fell asleep. But now scientists know that your brain is busy doing all sorts of things at night! It’s kind of like nighttime is your brain’s time to clean house.
When you’re asleep, your muscles and cells repair themselves. (In fact, some cells in your brain are 5 to 10 times more active when you’re asleep than when you’re awake!) Your immune system strengthens itself to help you fight off sickness. When you sleep, your brain also organizes the things you learned during the day. With all that activity going on, it’s amazing you get any rest at all!
“Night Night, Sleep Tight . . .”
How much sleep do animals need? That depends on the animal. Some animals sleep almost all day. Some hardly ever sleep. Check out this chart—do you wish you could be a brown bat or a giraffe?
Animal Amount of sleep per day
Brown bat 20 hours
Tiger 16 hours
Squirrel 15 hours
Cheetah 12 hours
Dolphin 10 hours
Guppy 7 hours
Horse 3 hours
Giraffe 2 hours
Newborn dolphins and killer whales sometimes don’t sleep for a whole month after they’re born.
In the wild, three-toed sloths sleep about 9 hours a day. Sloths that live in a zoo sleep about 15 hours a day. (Why do you think that happens?)
Most birds can sleep with one eye open, and they can sleep with only half of their brain at a time. The other half stays awake to watch out for cats and other predators. Scientists think some birds, like the albatross, can even sleep while they’re flying!
The golden dormouse balances on a small tree branch while it sleeps. If it feels the branch start to move, it knows another animal is coming, so it wakes up right away.
In Your Dreams
Sleep is a mystery, but dreams are even more mysterious. Most dreams happen in a stage of sleep called REM (Rapid Eye Movement), when your brain is really active. Most people have REM sleep 5 or 6 times a night, so that means 5 or 6 dreams a night. That’s more than 1,800 dreams a year! How many of your 1,800 dreams can you remember?
In the Bible, God often talked to people when they were asleep and dreaming. In 1 Kings 3:5-15, King Solomon dreamed that God came to him and told him he could ask for ANYTHING he wanted. Do you know what Solomon asked God for? He didn’t ask for lots of money or three magical wishes or a lifetime supply of cookies. Solomon asked for wisdom so that he would be a good king.
What would YOU ask for if God came to you in a dream?
Take the Sleep Quiz
Think you know a lot about sleep? Take this quiz and find out!
- True or False? Kids between the ages of 7 and 11 need about 8 hours of sleep every night.
- True or False? You grow more when you’re asleep than when you’re awake.
- True or False? If you don’t sleep enough during the week, you can catch up on your sleep over the weekend.
- True or False? Elephants don’t dream.
- True or False? Warm milk helps you sleep.
- True or False? Sunshine helps you sleep.
- True or False? The longest any human has ever gone without sleep is 4 days.
- False. Most kids that age need 10 to 11 hours of sleep a night.
- True! When you sleep, your body releases more “growth hormones”—chemicals that help you grow.
- False. Your body works best when you go to sleep and wake up at the same time every day. “Sleeping in” or trying to catch up on sleep doesn’t really help much.
- False. All mammals dream, but we don’t know what those dreams are like.
- True! Milk contains a chemical called tryptophan, which helps you sleep. Other foods that have tryptophan include oats, bananas, eggs, and turkey.
- True! People who get outside in the sunshine during the daytime sleep better at night.
- False. The record for going without sleep was set by Toimi Soini of Hamina, Finland, in 1964. Toimi stayed awake for 11 days, or 276 hours! (That would make most people really sick, so don’t try this at home.)
Who Needs a Lullaby?
Do you ever have trouble falling asleep? Here are some tips for getting a really great night’s sleep:
After dinnertime, don’t eat or drink things that have a lot of sugar and caffeine (things like sodas and chocolate can keep you awake).
An hour or so before bedtime, turn off the computer, the TV, and videogames so your brain can start to relax.
When it’s getting close to bedtime, turn the lights in your house down low. Bright lights make your body think it’s still daytime.
Turn down the heat and pull the shades in your room. If your room is cool, dark, and quiet, it’s easier to fall asleep.
In peace I will lie down and sleep,for you alone, LORD,make me dwell in safety.