Dreams

Comment: I thought this was interesting. I get it from a vocabulary program offered by Dr. Kennedy on his medical site.

Dreams:

Thoughts, visions, and other sensations that occupy the mind in sleep. Dreams occur during that part of sleep when there are rapid eye movements (REMs). We have 3 to 5 periods of REM sleep per night. They usually come at intervals of 1-2 hours and are quite variable in length. An episode of REM sleep may be brief and last but 5 minutes. Or it may be much longer and go for over an hour. About 80% of sleep is NREM sleep. If you sleep 7-8 hours a night, all but maybe an hour and a half is spent in dreamless NREM sleep.

Dreams are penetrable; it has been found experimentally that one can communicate with a person who is dreaming. The content of dreams is sometimes the topic of psychoanalysis. While this method of therapy is less common than it once was, some doctors still look at dreams as a diagnostic clue to medical disorders. For example, children with bipolar disorders have been found to frequently have a particular type of nightmares, and especially lucid dreams are a side-effect of certain medications.

These clues indicate that chemicals in the brain, as well as life events and our own preoccupations, influence our dreams. Dreaming is not uniquely human. Cats and dogs dream, judging from the physiologic features. So apparently do many other animals.

The word "dream" is traditionally traced back to an Anglo-Saxon word meaning joy, gladness, or mirth. However, "dream" more likely came from another word (from Sanskrit) meaning deception.