REM sleep stands for rapid eye movement sleep. People dream during the REM sleep cycle. Although the exact importance of dreaming remains unknown, a relationship among REM sleep, health and mental alertness has been established.
The REM Sleep Cycle
The REM sleep cycle is part of the larger sleep cycle. Sleep is split into two categories: REM sleep and NREM sleep. NREM sleep stands for non-rapid eye movement sleep and is split into four different stages:
- Stage one, during which the eyes are closed but the individual is easily awakened
- Stage two, or light sleep, when the heart rate slows and body temperature drops
- Stage three, when the body enters deep sleep
- Stage four, similar to stage three, but sleep is deeper.
REM sleep occurs after stage four.
The sleep cycle repeats several times a night, with the REM sleep cycle and light sleep cycle lengthening each time while the deep sleep cycles shorten. The average person spends about one-quarter of each sleep cycle in REM sleep.
During the REM sleep cycle, heart rate, blood pressure and breathing rates rise. The eyes twitch rapidly and mental activity resembles waking activity. The body enters a state of paralysis during the REM sleep cycle, so dreamers cannot act out their dreams.
REM Sleep: Health Effects
Scientists continue to debate the purpose of REM sleep. A person’s health suffers from a lack of REM sleep. The REM sleep cycle affects the brain’s learning centers, and a lack of REM sleep interferes with learning ability and memory. The possibility that REM sleep encourages learning may explain why infants experience long periods of REM sleep.
Health problems in lab rats develop from a lack of REM sleep, according to the National Institute of Neurological Disorders and Stroke (2007). Lab rats denied REM sleep cycles die within five weeks, a tiny fraction of a rat’s normal two-to-three year lifespan.
REM Sleep, Health and Sleep Disorders
REM sleep disorders disrupt the normal REM sleep cycle. People may get too little REM sleep or they may experience excessive quantities of REM, which reduces the amount of time spent in deep sleep. People with narcolepsy may enter REM sleep almost immediately after falling asleep.
A REM sleep behavior disorder occurs if the body doesn’t enter a state of paralysis during the REM sleep cycle. One of the most serious REM sleep disorders, REM sleep behavior disorder causes people to physically act out dreams.
Dreams associated with REM sleep behavior disorder are often violent. The sleeper talks, shouts, screams or lashes out at a bed partner. Punching, kicking, arm flailing and leaping out of bed are possible REM sleep behavior disorder symptoms. The violent nature of the disorder places both the sleeper and bed partner in jeopardy.
The causes of REM sleep disorders are often unknown. A REM sleep behavior disorder can be caused by substance abuse withdrawal, the use of antidepressants or neurodegenerative diseases such as Parkinson’s disease. The treatment of REM sleep behavior disorder begins with clonazepam, which proves effective in most cases.
Bengston, M. (2005). Sleep disorders: Dreaming and REM sleep. Retrieved August 20, 2010, from http://psychcentral.com/disorders/sleep/rem.htm.
eMedicine Health. (2007). REM sleep behavior disorders. Retrieved August 10, 2010 from www.emedicinehealth.com/rem_sleep_behavior_disorder/article_em.htm.
National Institute of Neurological Disorders and Stroke. (2007). Brain basics: Understanding sleep. Retrieved August 20, 2010, from http://www.ninds.nih.gov/disorders/brain_basics/understanding_sleep.htm.
Sleep Channel. (2007). Overview, waking, non-REM, REM, sleep cycles, factors, age. Retrieved July 25, 2007 from the Sleep Channel Web site: www.sleepdisorderchannel.com/stages/.