Sleep for the Memory

According to Boston Psychiatrist Chester Pearlman, evidence from both Europe and America is making 1976 "The Year of REM Sleep." Scientists have long known that REM (for the rapid eye movement during periods of dream sleep, which occur three to five times a night in 20-min. segments) serves crucial needs. One of those needs, Pearlman told the Paris conference, has now been clearly identified: REM dreaming is essential to consolidate memories --no dreaming, no long-term memory.

Some ten years ago, French Psychologists Vincent Bloch and Pierre Leconte showed that laboratory rats forgot how to do certain things if deprived of REM sleep after training. In a similar experiment by Pearlman, a rat that had mastered an intricate system of avoiding electric shocks to get food was deprived of REM sleep and then starved to death when tests were repeated.

Among other things, the evidence indicates that the student who stays up all night cramming for an exam is making a mistake. Says Pearlman: "You introduce a lot of facts that you really can't learn, because staying awake prevents it. The next day you won't be able to remember any of it, and you certainly will not be able to use any of it in the future --it is not part of you." A group of researchers at the University of Ottawa showed the same role of sleep in integrating recently learned material into long-term memory: among students enrolled in an intensive language course, those who were learning had an increase in REM sleep; those who were unable to learn had no such increase.

Pearlman and his colleague at the Boston Veterans' Administration Hospital, Psychoanalyst Ramon Greenberg, are among those who argue that REM sleep does more than aid memory: it also helps people cope with daily stress. Paradoxically, it is while sleeping that they assimilate traumatic experiences they have had during the day. In recording the sleep patterns of psychiatric patients, Pearlman and Greenberg found a rise in REM sleep occurred after stressful discussions. In an experiment with nonpatients, the need for REM sleep rose sharply after exposure to distressing movies. The researchers' conclusion: the memory function and coping function of REM sleep are linked. In both cases, the mind must deal with something it has not been prepared to face, and dream sleep makes it possible to consolidate the new material and make it part of oneself. "We know people generally repress the implications of situations for which they are not prepared," says Pearlman. "The situations usually appear in dreams the next time they sleep and there can be a resolution of the problem." Though the functions of sleep are far from being well understood, it is hardly just "rest." The REM period may well be one of the most exciting and active parts of the day.

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