Why do I have to go to bed so early?

Well, doctors have done a lot of research into the whole business of sleep. No one likes to miss out on the fun things that might happen while they are asleep, so the doctors wanted to know why we needed to do it and just how much sleep we absolutely have to have. It turns out that there are two reasons why we need to sleep.

First, our bodies do their growing while we sleep. Look at you: You're growing bigger and taller and stronger all the time, aren't you? This is because during the day, you eat foods that your body needs to increase your muscle and bone sizes. At night, while you're asleep, your body turns that food into you. Now that you're a little bit bigger and taller, you have to get lots of exercise so that your muscles will get stronger and will know what they are supposed to do for you. If I let you stay up too late, your body won't have enough time to do the right amount of growing.

The second reason is that while you are asleep, your mind sorts out all the things you saw and did and said during the day and all the things that were done and said to you. Some of these things are stored in your memory so you can use them later. Some things your mind just tosses away, even if you want it to remember them! Minds are strange things sometimes, aren't they? If I let you stay up too late, your mind won't have enough time to sort all the stuff it received during the day, and pretty soon you'd have a very large lump of stuff in your head that you don't understand and don't know what to do with.

Now, the reason you have to have as much sleep as you do is that the doctors have found that people your age have bodies and minds that just have to have that much sleep every night in order to do their jobs properly. There's no getting around it. Why, you can even get sick if you don't get enough sleep! As you get older and bigger, your body doesn't have as much of you left to make, so you need less sleep.

Even though your body needs ten hours of sleep now, when you're a teen-ager, you will only need nine hours, and when you get all grown up, you will need only eight hours. But if I let you stay up later now, at your age, I will be cheating your mind and body of the time they need to help you grow up, and I just can't do that to you.