Why Do We Need Sleep?

by Read Listen Learn

We do it every day because we need to. We feel terrible if we don’t. We shout and get angry for no reason. We can’t think well; our bodies feel tired; and we make stupid decisions. Another thing is we can’t remember very easily what people tell us. It makes no difference if that information is about our studies or what the boss said or what our family needs from the supermarket. And we have a lot more accidents. Of course, we are talking about sleep.

We often think sleep is one thing: it’s not. There are two kinds of sleep: the first is called Rapid Eye Movement (or REM). This is when our eyes move very fast from one side to the other, although they are closed. This is also the time when we dream and our brain is working as fast as when we are at work. The other kind of sleep is non-REM. This is when we just start to fall asleep or, on the other hand, are already in a deep sleep. Then our brain does nothing: in fact, it’s resting.

We need different amounts of sleep at different times in our lives. For instance, a child at primary school needs nine to eleven hours a night; a teenager needs about nine; and adults at least seven. When we get old, we need more sleep again, like when we were teenagers.

But it’s not just about how much sleep. It’s also about when we need it. Teenagers’ brains get tired in the early hours of the morning and they need to sleep later at night and, so, later in the morning. They aren’t lazy because they can’t get up in the morning. It’s their bodies. They’re telling them that they need more sleep. So, it’s just not true that going to bed early is always healthy.

In the U.S.A., some high schools now open late in the morning and close in the early evening: in fact, students at those high schools get higher grades because they are more awake. Later in life, that changes and we get tired in the evenings. It’s because of our ‘biological clock’, a body system that tells us when we feel tired and hungry and so on. This ‘clock’ runs differently at different times in our lives.

For some people, sleep is not just a problem because they can’t get up in the morning or feel tired at work in the afternoons. It’s much more serious. These people can’t go to sleep. They lie in bed and they wait and they wait and they wait... but sleep doesn’t come. Others fall asleep and then wake up after ninety minutes. We call this problem ‘insomnia’ – not sleeping although we are tired. Then there are other people who snore. They can fall asleep but they start to snore after a few minutes. This often means that their airways are blocked. Their bodies wake up so that they can begin to breathe again. This is dangerous because it means that their hearts and brains don’t get enough oxygen for a second or two. When it happens three or four times every night, it becomes a real problem.

But insomnia and stopping breathing when we are asleep are dangerous because we feel tired or want to close our eyes when we are in a meeting at the office or when we are driving. If we go twenty-four hours without any sleep, we drive like we are drunk. Another problem is that peptides in our bodies usually tell us when we are hungry and full. This does not happen when we are very tired. Our bodies stop making ‘leptin’, the peptide that tells us we are full, and we start making more ‘ghrelin’, which tells us we are hungry. So, late at night before we go to bed, we often feel very tired and want sugar or carbohydrates. These make us fat.

People do different things to fall asleep. Some go to bed early; some drink lots of coffee so that the caffeine keeps them awake and they can do something if they can’t fall asleep; others lie in bed and read or watch TV or play on the Internet. All these are mistakes. Very soon, our bodies start to believe that bed is for television or chatting with friends on the Internet. Our brain must think that bed is for sleep and we must not give it different messages, like it’s OK to read there. If the brain starts thinking that, it gets harder and harder to fall asleep. The most important thing to do in bed is nothing. Don’t play or watch or listen or chat! Do nothing!

If you still don’t fall asleep and the problem continues, you can look at some websites. They give you good ideas about sleeping. Of course, if the problem goes on for three months or more, go and see a doctor!