Dreams

Dreams have fascinated people for millennia. Ancient people sought portents of the future in dreams. Not-so-ancient people, such as Sigmund Freud, sought information about the psyche: he felt that an examination of dreams could help a psychoanalyst guide a person in the resolution of inner conflicts.

In the 20th century, the function of dreams has continued to be debated. Some experts have thought they must be vital to our well-being–otherwise, why would we have them?–while others have thought they’re just unimportant byproducts of our brains’ biochemistry.

Over the years, we have learned what our dreams have in common. For example, research indicates that 75 percent of dreams are in color and two thirds include sound, but only about one percent include touch, taste or smell. Men most often dream about men; women dream about men and women equally. Women’s dreams are typically more emotional and have fewer people in them, though they tend to include more social interaction and more clothes: men tend to dream about money, weapons and nudity. We dream about 90 minutes every night, but we usually only remember a dream every four or five days.

Dreaming takes place during the portion of sleep known as REM (rapid eye movement) sleep, which lasts from 10 minutes to half an hour, four to six times a night. During REM sleep your previously comatose brain suddenly erupts with activity. Your eyes move rapidly under your closed eyelids, and your heart rate, breathing rate and blood pressure, which dropped with your body temperature as you fell asleep, all go up. (Fortunately, despite all this activity, your body remains effectively paralyzed. Otherwise you might act out your dreams, which, if you’ll recall a few of your more vivid sleep-time experiences, could be embarrassing, if not downright dangerous.) REM sleep is sometimes called paradoxical sleep, because even though the brain seems to be as electrically active as when we’re awake, it’s completely unresponsive to the outside world.

If we don’t get enough REM sleep, we make up for it with longer-than-usual periods of REM sleep during our next sleep or next several sleeps, which suggests REM activity is somehow vital to our well-being. That suggests that dreaming, too, is important–and a new study may indicate why.

As reported in the most recent issue of the magazine Science, Allen Braun of the National Institutes of Health and Thomas Balkin of the Walter Reed Army Institute of Research conducted PET scans of several sleeping subjects. In a PET scan, mildly radioactive glucose is injected into the blood. Since actively firing nerve cells need more blood, they attract more of the radioactive glucose and light up the scanner, indicating which parts of the brain are active.

It turns out that in sleep the frontal lobes, which integrate information, help us interpret the outside world, and contain working memory, are shut down–while much of the rest of the brain is highly active.

That could explain why our dreams are so vivid and gripping, even though they don’t make a lick of sense. With our frontal lobes out of the picture, dreams are being driven by emotion, not logic. And without working memory, the dreaming brain forgets what just happened in the dream–which is why, in a dream, you can step out of your kitchen onto the Empire State Building, while your companions morph from friends to large shaggy dogs. The absence of working memory may also explain why it’s hard to remember dreams in detail.

The authors of the study say their results suggest that dreams are basically a test program run by the body to see if the brain has had enough sleep yet and, if it has, to wake it up. Dreams, in this view, are not necessary; they’re just a side effect of this “test program.”

But others scientists, such as Dr. Allan Hobson, a dream expert at Harvard Medical School, still think dreams are more important than that. Dr. Hobson points out the study’s finding are consistent with the theory that we consolidate memories while dreaming. If dreams are under the control of the emotional centers of the brain, he says, then maybe during dreams memories are being read out and filed away in terms of their emotional importance. The hippocampus, where memories are processed for long-term storage, is one of the regions active.

Obviously there’s still lots of research to be done on dreams…and I hereby volunteer to help!

(Yawn.) Just point me to the couch.

Permanent link to this article: https://edwardwillett.com/1998/12/dreams/

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