9781422285770

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A LIFETIME OF SLEEP

Most people spend about a third of their lives sleeping. If a person sleeps eight hours every night, then by the time she is 15 years old, she will have spent a full 5 years asleep. By the time she’s 75 years old, she’ll have slept for 25 years. That sounds like a lot, but some animals sleep even more. Some armadillos, opossums, and sloths spend as much of 80 percent of their lives sleeping!

many nights, it’s nothing to worry about. But if you have insomnia often, you could have a health problem. Everyone needs sleep, but what is it, anyway? Why do we need it, and why can sleep sometimes be so hard to get? What Is Sleep? Sleep is a time of physical rest. Our bodies are mostly still, and our eyes are usually closed. Our minds are not aware of the outside world. But sleep is a temporary state. Someone who is asleep can wake up. People once thought that the brain stopped working when people were asleep. It was thought that the brain was resting along with the body. Today we know the opposite is true. The brain of a sleeping person is actually very busy! Scientists tell us there are two types of sleep, each with a different level of brain activity: rapid eye movement (REM)