Hobson's research, moreover, has led to his theory that REM sleep is a necessary function of life. "It's just a hypothesis at this point, but it seems like REM is tied to metabolism. When animals are REM-deprived or sleep-deprived, they die. They may eat more, but they lose metabolic control. They also lose thermoregulation, which points to a problem with caloric control."

Hobson says that the metabolism is affected because the aminergic neurons, which rest during REM sleep, get a chance to replenish their supply of neurotransmitters. These chemicals control the functions of learning, memory and attention spans. he says.

While such ideas are as yet mere hypotheses. Hobson says he has already started research to prove his ideas. He and his colleagues are planning experiments to study sleep deprivation in rats.

"These things are speculations now, but soon we will know why dreams function," Hobson says. "The next 20 years will see a great deal of research devoted to the subject."

"Hobson and McCarley came out with a model which is a very good way of looking at things. It has wide popularity. They are a highly thought-of neurophysiological team." says John H. Herman, associate professor of psychiatry at Southwestern Medical School in Dallas.

'Bizzareness'

Another aspect of Hobson's research involves the study of dreams themselves and the analysis of their surreal content. "All dreams have several things in common," he says. "There is memory loss, hypervisual imagery, bizzareness, poor logic and vagueness. We began to study what constituted 'the bizzare.'"

According to Hobson, "bizzareness" in dreams is defined as discontinuity or incongruity in the plot line. Sometimes people dream the physically impossible, like flying, but more often, he says, there are subtle changes in the unconscious world.

Hobson says that bizzareness in people's dreams takes many different forms, such as total confusion, loss of clarity in thinking and rapid scene changes. "We found that there was a lot of cognitive uncertainty--people have trouble remembering what is going on in their dreams," he says.

A Freudian Touch

In Freud's The Interpretation of Dreams, the psychologist argues that dreams allow the unconscious to send secret messages to the brain, releasing information pertaining to repressed desires and emotions.

Freud's theory, suggested around the turn of the century, rested on the assumption that while dreaming, the brain processes information from daytime activities and releases unconscious desires through symbols during dreams. According to Freud, if a woman dreams about dancing with a rabbit, she might actually be expressing a desire to become involved with a friend named Robert, since Robert and rabbit are spelled similarly.

While Hobson and McCarley say they do not disagree with Freud's theory of dream expression, they assert that the REM stage involves more complex activities than rehashing past experiences.

"We're not speaking against symbolic interpretation of dreams," Hobson says. "Sometimes there's no need to do interpretation at all. What we're thinking about in our sleep is often embarrassingly obvious. But there is enough going on at face value to keep us busy without getting into symbol stuff."