Sleep, sleep studies and sleep-disordered breathing: basic knowledge for the anesthesiologist.

PURPOSE OF REVIEW: To provide a basic understanding of sleep physiology, the pathophysiology of sleep-disordered breathing and the processes applied in undertaking and assessing sleep studies.

RECENT FINDINGS: It has become increasingly apparent that obstructive sleep apnoea is associated with heightened perioperative risk. Furthermore, the condition still remains under-diagnosed in patients presenting for surgery.

SUMMARY: This review describes the physiology of sleep including sleep stages, sleep monitoring, the normal hypnogram and investigation from simple overnight pulse oximetry to full polysomnography. The pathophysiology of sleep-disordered breathing is discussed; from simple snoring through obstructive sleep apnoea to obesity hypoventilation syndrome. The relationship to metabolic syndrome is explored.Salient points in the interpretation of sleep study reports are presented.