Why do we dream?

"Why do we dream?" was the question posed by the BBC Horizon TV program last night. It was a fascinating program that investigated this most hidden of mysteries.

Many people are now aware that Rapid Eye Movement or REM periods during sleep indicate that a person is dreaming but now studies have shown that we also dream between these REM episodes. What was most interesting though was that the nature of the dreams in REM sleep appears to be different to the dreams in non-REM sleep.

When test subjects in REM sleep were woken up, their dreams seemed to be of a negative or doubting nature whilst when woken in the non-REM dream periods, the sleepers reported a greater number of positive emotions.

One researcher postulated that this may help explain some forms of depression. The idea being that a person with depression would be entering the REM stage of sleep more often and therefore staying in the negative mood for longer periods during sleep. Whether this is a cause of depression or a side effect of it was at least to this viewer unclear.

It was a fascinating program though, you can watch it again using the BBC iPlayer service (this may not work outside the UK). Follow this link for the program's iPlayer page.