Dreams Serve a Purpose

Dreams act as your brain's rehearsal system for waking life. In studies of rats, the exact firing patterns recorded while an animal ran a maze reappear during sleep, in the same sequence but sped up — the brain rehearsing the route in fast-forward to lock in spatial learning.

This rehearsal also tunes emotion and creativity. People repeatedly woken during REM sleep show measurable dips in learning, creative problem-solving, and emotional control the next day, even when their total sleep time is unchanged.