Physiology
Physiologically, certain neurons in the brain stem, known as REM sleep-on cells, (located in the pontine tegmentum), are particularly active during REM sleep, and are probably responsible for its occurrence. The release of certain neurotransmitters, the monoamines (norepinephrine, serotonin and histamine), is completely shut down during REM. This causes REM atonia, a state in which the motor neurons are not stimulated and thus the body's muscles do not move. Lack of such REM atonia causes REM behavior disorder; sufferers act out the movements occurring in their dreams. Heart rate and breathing rate are irregular during REM sleep, again similar to the waking hours. Body temperature is not well regulated during REM. Erections of the penis (nocturnal penile tumescence or NPT) normally accompany REM sleep. If a male has erectile dysfunction (ED) while awake, but has NPT episodes during REM, it would suggest that the ED is from a psychological rather than a physiological cause. In females, erection of the clitoris (nocturnal clitoral tumescence or NCT) causes enlargement, with accompanying vaginal blood flow and transudation (i.e. lubrication). During a normal night of sleep the penis and clitoris may be erect for a total time of from one hour to as long as three and a half hours during REM.
Read more about this topic: Rapid Eye Movement Sleep
Famous quotes containing the word physiology:
“A physician’s physiology has much the same relation to his power of healing as a cleric’s divinity has to his power of influencing conduct.”
—Samuel Butler (1835–1902)
“I have more in common with a Mexican man than with a white woman.... This opinion ... chagrins women who sincerely believe our female physiology unequivocally binds all women throughout the world, despite the compounded social prejudices that daily affect us all in different ways. Although women everywhere experience life differently from men everywhere, white women are members of a race that has proclaimed itself globally superior for hundreds of years.”
—Ana Castillo (b. 1953)
“Now the twitching stops. Now you are still. We are through with physiology and theology, physics begins.”
—Alfred Döblin (1878–1957)