The Secrets of Sleep

from Ducks Unlimited's Puddler magazine Summer 1998

As we saw in Special Feature, sleep or rest are important to all animals, not just people. Sure, there are times you'd rather do anything than sleep, but you need to hit the hay to stay healthy. Why is sleep so important and how does it work, anyway? For people and animals that truly sleep, the answers basically are the same.
 

What's so great about sleep?
The average person spends one-third of his or her life sleeping! Why? Scientists say we need sleep to allow our bodies to rest. As we sleep, our bodies can repair and rebuild cells to keep us healthy. Sleep gives our brains a break, too. During the day, our senses gather lots and lots of information. During sleep time, the brain can sort through this information to make better sense of it. Important stuff gets saved as memories.
Human babies (and animals) spend most of their time sleeping. When you think about how many new things they must learn, you can understand why! As adults, different people need different amounts of sleep. Still, everyone needs a regular sleep schedule. Scientists have studied what happens when people skip sleeping for a few days. They have trouble keeping their thoughts straight. They even imagine they're seeing things!
 

What happens during sleep?
Imagine lying in your bed at the end of the day. Your eyelids close and your body feels very relaxed. As you drift off to sleep, your heartbeat and breathing slow down. Your body temperature drops, too. At first, you're "dozing." A noise might wake you easily. In about an hour, though, you're in a deep sleep. It would be difficult for you to wake from this kind of sleep.
In time, your sleep changes. Your heartbeat and breathing speed up. Your eyes start moving back and forth. You might roll over. You're in a light sleep again. This is when you dream. You will spend all night switching from a light sleep to a deep sleep. Each cycle takes about one and a half hours.
 

What is dreaming all about?
All people dream. People don't always understand or even remember their dreams. Usually, dreams tell a story about what's happening in your life at the time. Sometimes, though, dreams can seem pretty wild. Have you ever dreamed you could fly or you were in a movie? What do these dreams mean?
You can find lots of books that explain what you see in your dreams. Scientists think your dreams send messages about how you feel about things that are happening to you. You also see pictures your brain comes up with as it sorts through new information and matches it to what you already know.
Most people have about five or six dreams each night. If you wake during a dream, you might remember it. Some people write down their dreams as soon as they wake up so they can remember them.
 

How do scientists know what happens during sleep?
Did you know your brain gives off electricity? It's true! Of course, it isn't enough electricity to make a light bulb glow! This electricity is called a brainwave. Doctors have a machine that can measure brainwaves. Wires attached to a person's head "feel" the brainwaves. This information gets recorded as wavy lines on a piece of paper. During deep sleep, brainwaves get larger and slower. During dream times, brainwaves get shorter and faster.
 

Do animals dream?
Scientists have studied the brainwaves of animals during sleep, too. Some of them show the same patterns of deep sleep and dream sleep that people experience. So far, scientists have only found these patterns in reptiles, birds and mammals. Does this mean that animals dream? Since they can't talk, this is one secret of sleep we still haven't solved. When we see a dog "running" and whining in its sleep, though, it sure seems like it's dreaming.