Sleep apnea is a common disorder in which breathing stops during sleep for 10 seconds or more, sometimes more than 300 times a night. The hallmark of the disorder is excessive daytime sleepiness and compromised quality of life, including significant social and emotional problems. There are two main types of sleep apnea. ''Obstructive sleep apnea'' may represent cessation of breathing due to mechanical blockage of the airway; ''central sleep apnea'' appears to be related to a malfunction of the b...