Although the exact role of sleep in humans and other animals has not been clearly determined, disruption of sleep can have serious consequences for the health of the affected individual. Disorders of sleep can result from a number of conditions, all with varied causes and associated symptoms. For example, one of the most common conditions resulting in disturbed sleep is obstructive sleep apnea syndrome. In this condition, patients experience either a relative collapse of the airway resulting in reduced airflow (hypopnea) or complete airway closure with resultant apnea. These episodes may occur hundreds of times per night with associated brief arousals and severely disrupted sleep continuity. The patient experiences significant and excessive daytime somnolence and may fall asleep frequently during the day, including while driving.
Disorders of Sleep May Be Related to Sleep Stage
Other disorders result from disturbances during specific stages of sleep. Sleep is normally separated into...