Polysomnography and Sleep Disorders

The classification of sleep disorders is based both on clinical and neurophysiological criteria and is undergoing constant refinement. Sleep disorders can be caused by either a primary disorder of a mechanism controlling sleep or inadequate function of an end organ, such as the upper airways and lungs. Understanding the physiology and pattern of normal sleep is an important foundation for interpreting the clinical symptoms, signs, and neurophysiological abnormalities observed in patients with sleep disorders. The term polysomnography refers to the simultaneous recording of multiple sleep parameters, including a limited electroencephalogram, respiratory parameters, chest excursion, limb movements, and the electrocardiogram. Polysomnography is important for assessing a variety of sleep disturbances, including disorders such as sleep-related breathing disorders (including obstructive sleep apnea), rapid eye movement behavior disorder, and periodic movements of sleep. The multiple sleep latency test and maintenance of wakefulness test are studies that are especially useful in the evaluation of narcolepsy and other hypersomnias.