3. Why do we dream?
Dreaming occurs chiefly during REM sleep, when the cerebral cortex is buzzing with activity, apparently consolidating memories. One theory is that dreams are simply the cortex’s attempt to make sense of it all. Barraged with a stream of random activity, you do your best to piece it into some semblance of a story.
Others don’t think it’s so random. One popular theory says dreams are practice for dealing with danger. The amygdalae – the seat of the fight-or-flight response – as well as brain areas associated with running and fighting are unusually active during REM sleep. We rehearse outrunning a lion so we have some experience if it were to happen.
Another possibility is that dreaming is a way to work through problems, ideas and emotions without the constraints of logic. Interestingly, the activity of REM sleep is centred in the midline of the brain, associated with emotions. In contrast, there’s little activity in areas associated with logical thinking or recall of details.