A significant proportion of the population has chronic sleep problems necessitating an increasing involvement by the primary care physician. Also, the general patient population is becoming more familiar with these disorders and is seeking assistance. Because sleep studies are expensive and time consuming, adhering to the recognized indications for testing reduces the number of inappropriate studies. Under most circumstances, individuals with excessive daytime sleepiness and symptoms suggestive of obstructive sleep apnea are candidates for polysomnography. Other individuals with parasomnias or difficult-to-treat insomnia are also candidates for testing. In some circumstances, procedures designed to assess sleepiness may also need to be used to ascertain the impact of the disorder on daytime functioning and may be part of evaluations involving the transportation industry. Only after taking a thorough history and doing a physical examination can the physician make an accurate determination of the appropriate study type.