National Cancer Institute
U.S. National Institutes of Health | www.cancer.gov
In English | En español
NCI Home
Cancer Topics
Clinical Trials
Cancer Statistics
Research & Funding
News
About NCI
Dictionary of Cancer Terms
In English   En español
Page Options
Print This Page
More NCI Dictionaries
NCI Drug Dictionary

Glossary of Statistical Terms

NCI Dictionary of Genetics Terms

Terminology Resources
Quit Smoking Today
Search for
# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
In English   En español

sleep stage

 One of 5 parts or stages of the sleep cycle based on the type of brain activity that occurs during the stage. During stages 1 to 4, a person will feel drowsy, fall asleep, and move into a deep, dreamless sleep. Stage 5 is called rapid eye movement (REM) sleep, and it is during this stage that dreams occur. 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 sleep (light to deep sleep).



Previous Definitions:skinning vulvectomy, SL-11047, SLE, sleep apnea, sleep disorder
Next Definitions:sleeve lobectomy, sleeve resection, slippery elm, slit-lamp biomicroscopy, slit-lamp eye exam

A Service of the National Cancer Institute
Department of Health and Human Services National Institutes of Health USA.gov