[The multiple sleep latency test in the diagnosis of narcolepsy and idiopathic hypersomnia].

The diagnostic differential between narcolepsy and idiopathic hypersomnia may be difficult in those cases which clinically manifest only hypersomnia and the nocturnal polygraphic study does not show any differences between both diseases, particularly when the beginning of REM sleep is not presented in narcoleptic patients. The multiple sleep latency test is an objective test of daytime hypersomnia in both diseases. Moreover, if 2 or more REM periods are registered altogether in the 4 or 5 siestas studied, the test is highly suggestive of narcolepsy and permits sure differentiation with idiopathic hypersomnia. In the present study, the multiple sleep latency test permitted the diagnosis of the cases of oligosymptomatic narcolepsy and absence of the beginning of REM sleep.