NREM sleep

NREM sleep Non-rapid eye movement sleep, dreamless sleep. During NREM sleep, the brain waves seen on an electroencephalogram (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 four stages of increasing depth, and the fourth and deepest stage eventually leads to REM sleep. About 80 percent of sleep is NREM sleep. See also REM sleep; sleep.