The use of sleep studies in neurologic practice.

Polysomnographic studies have been shown to be useful in the diagnosis of many sleep disorders, particularly those associated with impaired respiration during sleep or impairment of daytime alertness. As with any test, unless it is performed under ideal conditions, the amount of information obtained may be limited. Because of the interaction between nighttime sleep and daytime alertness, disorders associated with impaired alertness usually require at least 24-hour assessment. The polysomnogram and MSLT, although detailed and time consuming, are essential for the accurate diagnosis of many sleep disorders. If a primary sleep disorder is suspected, polysomnographic testing, particularly early in the patient's evaluation, may obviate unnecessary neurologic and medical tests, which yield little information in the assessment of disorders of sleep and wakefulness.