Bevin Pelvin, of King's High School, asks :-

How and why do people dream?

David Menkes, of the Department of Psychological Medicine and Behavioural Science at the Otago Medical School, responded.

Dreaming has fascinated all sorts of people: philosophers, mystics, doctors, psychologists. The question of how dreaming takes place has been studied in detail by scientists using physiological techniques. Clusters of nerve cells in the brain stem are known to control sleep and arousal. One set of these, called the raphe nuclei, are particularly involved in rapid eye movement (REM) sleep, the phase during which dreaming occurs. When the raphe cells stop firing, dream imagery can occur, probably in the same parts of the brain which normally process 'real' visual information. Interestingly, drugs such as LSD artificially supress raphe cell activity, which might explain why such drugs can cause hallucinations.

The 'why' question has no definite answer, but dreaming is thought to be important to maintain some sort of psychological balance in people. Its importance is shown partly by the nasty effects of depriving people of dreaming sleep: any of us will get irritable and tired if subjected to REM sleep deprivation. Psychologists and others believe that dreaming allows us to process thoughts and issues left over from waking life -- this idea has merit since most of us are aware how a major life event often appears in dreams. Dreaming also allows 'censored' material to be processed, which can have both pleasant and alarming results!