鈥淭he interpretation of dreams is the royal road to a knowledge of the unconscious activities of the mind.鈥� So said Sigmund Freud. Today, most researchers reject his belief that dreams are expressions of our unconscious desires, but the fascination with why we dream is stronger than ever.
Dreams are not meaningless, and they are certainly not useless. For a start, they are crucial for processing emotions. 鈥淒reams modulate the emotions 鈥� they keep them within a certain range,鈥� says Patrick McNamara of Boston University. New research has found that naps consolidate emotional memories 鈥� and the greater the amount of rapid-eye-movement (REM) dream sleep, the greater the processing of these memories (Cerebral Cortex, vol 19, p 1158).
One idea is that REM dreams allow us to relive powerful emotional memories, but without the rush of stress hormones that accompanied the real experience (快猫短视频, 21 February, p 34). In this way, we keep the memory but the emotion accompanying it gradually lessens.
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REM dreaming also helps other types of memory and problem solving. People are better able to recall lists of related words and the connections between them after a night鈥檚 sleep than after the same time spent awake during the day.
It has recently become apparent that not all dreaming occurs in REM sleep, and there are hints that non-REM dreams have their own special function. By waking students during both REM and non-REM sleep, have discovered that REM dreams are more story-like, with more emotion, more aggression and more unknown characters than non-REM dreams, which often involve friendly social interactions (Psychological Science, vol 16, p 130). McNamara thinks that by simulating aggressive encounters, REM dreams help us cope with real aggression, whereas non-REM dreams support cooperative behaviour.
The content of dreams can be influenced by external factors such as scents, or even the Earth鈥檚 geomagnetic field, but there seem to be some reoccurring themes. Many REM dreams contain unknown males, usually in aggressive social interactions with the dreamer. The discovery of universal themes could herald a return to the study of the meaning of dreams, this time based on science. 鈥淚t suggests that a certain kind of dream interpretation may be possible,鈥� McNamara says.
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