Comparative polysomnographic study of narcolepsy and idiopathic central nervous system hypersomnia

Patients with a primary diagnosis of narcolepsy or idiopathic CNS hypersomnia seen at Stanford University Sleep Disorders Clinic over a 5-year period were studied retrospectively. The two patient groups were compared with respect to blood pressure, Minnesota Multiphasic Personality Inventory (MMPI) psychological profile, nocturnal sleep structure, prevalence and severity of sleep apnea and periodic leg movements in sleep, and daytime sleep tendency. Narcoleptic patients tended to have higher blood pressure, higher prevalence of abnormally elevated MMPI scores, more abbreviated and more disrupted sleep at night, and greater daytime sleep tendency. Sleep apnea and periodic leg movements were more prevalent in narcoleptic patients, but only periodic leg movements in sleep were more prevalent in narcoleptic patients than in the general population. Periodic leg movements during REM sleep were observed in more than one-third of narcoleptic patients, which may be an important pathophysiologic feature of this disorder.