NCI Dictionary of Cancer Terms
The NCI Dictionary of Cancer Terms features 7,777 terms related to cancer and medicine.
Browse the dictionary by selecting a letter of the alphabet or by entering a cancer-related word or phrase in the search box.
- REM sleep
- listen (… sleep)
- One of the five stages of sleep. During REM sleep, the eyes move rapidly while closed and dreams occur. REM sleep is the lightest stage of sleep, during which a person may wake easily. During several hours of normal sleep, a person will go through several sleep cycles that include REM sleep and the 4 stages of non-REM (light to deep sleep). Also called rapid eye movement sleep.