Why do we dream?

Scientists do not have one definitive answer, but several well-supported ideas explain why we dream. Most dreaming happens during REM sleep, when the brain is highly active. One leading theory is that dreaming helps process emotions and consolidate memories, sorting through the day's experiences and strengthening what matters. Another view is that it lets the brain safely rehearse responses to threats or social situations. Some researchers see dreams partly as a by-product of the brain reorganising itself overnight. What is clear is that sleep and dreaming support learning, mood, and mental health, which is why poor sleep leaves you foggy and irritable. Most dreams are quickly forgotten unless you happen to wake during them.