The definitions used in this glossary of terminology either have been provided by the authors of the articles, or have been extracted wholly or in part, or paraphrased from the following sources: The American Medical Association Encyclopedia of Medicine, Charles B. Clayman, MD, Medical Editor, Random House, New York, 1989; Biotechnology from A to Z, 2d Edition, William Bains, Oxford University Press, New York, New York, 2002; A Dictionary of Genetics, 6th Edition, Robert C. King and William D. Stansfield, Oxford University Press, New York, New York, 2002; Dorland's Illustrated Medical Dictionary, 29th and 30th Editions, W. B. Saunders Company, Philadelphia, 2000, 2003; Genes VII, Benjamin Lewin, Oxford University Press, New York, New York, 2000; The Gale Encyclopedia of Genetic Disorders, Volumes I and II, Stacey L. Blachford, Ed., Thomson Learning, New York, New York, 2002; The Merriam-Webster Dictionary, Merriam-Webster, Inc., Springfield, Massachusetts, 1997; Molecular Biology of the Cell, 3rd Edition, Bruce Alberts, et al., Garland Publishing, 1994; The Random House Dictionary of the English Language, Unabridged Edition, 1966; Webster's Ninth New Collegiate Dictionary, 1991.

DEFINITION:

REM sleep

The period of sleep during which the brain waves are fast and of low voltage, and autonomic activities, such as heart rate and respiration, are irregular. This type of sleep is associated with dreaming, mild involuntary muscle jerks, and rapid eye movements (REM). It usually occurs three to four times each night at intervals of 80 to 120 minutes, each occurrence lasting from 5 minutes to more than an hour. In adults, about 20 percent of sleep is REM sleep and 80 percent is NREM (non-rapid eye movement) sleep. Called also desynchronized sleep, paradoxical sleep , and rapid eye movement sleep .