As the stage in which people dream each night, rapid eye movement (REM) sleep can bring euphoria, terror, and even genuine harm in some instances. On transition into REM sleep, your body enters a fascinating state. True to its name, REM sleep results in characteristic, swift, saccadic eye movements. But many other features of REM sleep are noteworthy. During REM sleep, activity in some brain regions is even higher than during wakefulness, so it is little surprise that it is from this sleep stage that you naturally arise each day. This state has therefore been dubbed the “gateway to waking”. But while your brain is highly active in REM sleep, your muscles are actually paralyzed (other than your heart and respiratory muscles). For this reason, REM sleep is sometimes known as “paradoxical sleep”. But what exactly is REM sleep actually for? In this show, Dan speaks with Professor John Peever, Director of the Centre for Biology Timing and Cognition at the University of Toronto. Professor Peever’s research focuses on how the brain regulates wakefulness and sleep, and our discussion focuses on REM sleep.