What does REM stand for?

REM stands for rapid eye movement. During REM sleep, your eyes move around rapidly in a range of directions, but don't send any visual information to your brain.That doesn't happen during non-REM sleep. First comes non-REM sleep, followed by a shorter period of REM sleep, and then the cycle starts over again. Dreams typically happen during REM sleep. REM is the phase of sleep in which most dreams occur.

During REM sleep, a person’s brain activity, breathing, heart rate, and blood pressure increase, and the eyes move rapidly while closed. The muscles in the arms and legs become temporarily unable to move. REM sleep is thought to play an important role in memory and learning. During normal sleep, a person goes through four to five sleep cycles that last about 90 minutes each and include both REM sleep and non-REM sleep (light to deep sleep).