REM sleep: REM sleep is the portion of sleep when there are rapid eye movements (REMs).
Dreams occur during REM sleep. We typically have 3 to 5 periods of REM sleep per night. They occur at intervals of 1-2 hours and are quite variable in length. An episode of REM sleep may last 5 minutes or over an hour. About 20% of sleep is REM sleep. If you sleep 7-8 hours a night, perhaps an hour and half of that time, 90 minutes, is REM sleep.
REM sleep is characterized by a number of other features including rapid, low-voltage brain waves detectable on the electroencephalographic (EEG) recording, irregular breathing and heart rate and involuntary muscle jerks.
By contrast, NREM (non-REM) sleep is dreamless sleep. During NREM, the brain waves on the EEG are typically slow and of high voltage, the breathing and heart rate are slow and regular, the blood pressure is low, and the sleeper is relatively still. NREM sleep is divided into 4 stages of increasing depth of sleep leading to REM sleep. About 80% of sleep is NREM sleep. If you sleep 7-8 hours a night, all but maybe an hour and a half is spent in dreamless NREM sleep.
n. A stage in the normal sleep cycle during which dreams occur and the body undergoes marked changes including rapid eye movement, loss of reflexes, and increased ...
Learn about the stages of sleep -- rapid eye movement or REM sleep and non rapid eye movement or NREM sleep.
Brain activity is quite intense at this stage. ... By Susan Pitman REM, or rapid eye movement sleep, is the fifth of the five stages of sleep most people go through each night.
Medical Author: ABM Salah Uddin, MD Medical Editors: Erasmo A Passaro, MD; Francisco Talavera, PharmD, PhD; Stephen Berman, MD, PhD. REM Sleep Disorder Overview
REM sleep seems to help prevent seizures that begin in one part of the brain from spreading to other brain regions, while deep ...