Diurnal and nocturnal sleep in narcolepsy with cataplexy

Narcolepsy is an under-recognized disease, but classically reported as one of the most severe conditions of chronic hypersomnia. Excessive daytime sleepiness is usually the first symptom to appear in childhood or in young adulthood, occurring daily, often irresistible, with short duration, capable of restoring normal vigilance for one to several hours, and associated with dreaming. In contrast, disturbed nocturnal sleep is clearly underestimated in that condition and, even if not included in diagnostic criteria, this complaint may be considered as the fifth component in addition to the narcolepsy tetrad. The presence of poor sleep at night may represent a significant and severe symptom in patients, especially with the evolution process. The diagnosis of narcolepsy with cataplexy is essentially clinical, but requires, whenever possible, a nocturnal PSG recording followed by an MSLT showing short mean sleep latencies and the presence of sleep-onset REM (REM) periods. Typically, the nighttime sleep of narcoleptics is highly fragmented with several long awakenings that may be associated with dissociated sleep/wake states, abnormal movements or behaviours during REM or non-REM (NREM) sleep, periodic leg movements during wakefulness and sleep, and sleep-disorder breathing. All narcolepsy symptoms and associated conditions need to be considered in the management of the disorder, but daytime sleepiness in narcolepsy seems independent of the amount and quality of nighttime sleep. © 2010 Springer-Verlag New York.