Dreams

Dear Dr. Universe,

Why do we dream?

Pat Caraher - Pullman, Washington

When I asked Barbara Hammond this question, the first thing she said was, "Who knows?"

Barbara Hammond is a psychologist at Washington State University. What she means is that a lot of people have some interesting ideas about dreams. But that's about it. By the time you finish reading this, you'll know much of what we know for certain about dreams. You're about to become a dream expert.

One thing we do know is WHEN we dream. That's during a period of sleep called "REM sleep." REM means rapid eye movement. During REM, your eyes are moving around a lot even though they're closed. Your brain is also very busy--and you're dreaming.

Hey, I'm no Sigmund Freud, but who's a psychologist to turn to when they have a weird dream they want to talk about?

Another thing that happens during REM is that your muscles are basically paralyzed. You know those dreams where you're trying to run away from something, but your legs are really, really heavy?

Now back to WHY. According to Ms. Hammond, there are two sets of explanations. First there's the "physiological" set.

"Physiological" has to do with how the body works. Some scientists think maybe

we dream in order to exercise our brains. When you're awake, messages are constantly speeding among all your billions of brain cells to keep you moving and thinking and digesting and so on. So the idea is that when you're asleep, dreams exercise the "pathways" between the brain cells. Personally, I like this idea of exercising while I sleep.

There are a couple of things that help this idea make sense. The first couple years of your life are the most intense for learning. That's also when you have the greatest amount of REM sleep -- which means you probably dream an awful lot.

Another thing--your brain waves during REM sleep look about the same as your brain waves while you're awake. (Brain waves are electrical patterns that show up on a machine that measures the brain's activity.) During other parts of sleep, the brain waves look very different.

Then there's the "psychological" set of ideas about why we dream. Psychology has to do with your thoughts and emotions.