Sleep

The natural periodic suspension of consciousness during which the powers of the body are restored.

APNEA Sleep apnea is caused by recurring interruption of breathing during sleep because of obstruction of the upper airway by weak or malformed pharyngeal tissues that results in hypoxemia and in chronic lethargy during the day; called also obstructive sleep apnea syndrome.

REM SLEEP A state of sleep that recurs cyclically several times during a normal period of sleep and is characterized by increased neuronal activity of the forebrain and midbrain