An uncomfortable environment or continuous positive airway pressure (CPAP) intolerance may cause poor sleep efficiency during polysomnography and result in a poor-quality study. Unsatisfactory polysomnograms often must be repeated. Nonbenzodiazepine hypnotics may improve sleep efficiency without disruption of sleep architecture. We hypothesized that premedication with zolpidem improves polysomnogram quality and decreases the need to restudy.