Differences in findings of nocturnal polysomnography and multiple sleep latency test between narcolepsy and idiopathic hypersomnia

ObjectivesTo compare differences in nocturnal and daytime polysomnographic findings between narcolepsy (NA) with and without cataplexy (CA) and idiopathic hypersomnia without long sleep time (IHS w/o LST).MethodsNocturnal polysomnography (n-PSG) and multiple sleep latency test (MSLT) findings were compared among subjects with NA with CA (n = 52), NA without CA (n = 62), and IHS w/o LST (n = 50).ResultsThe NA with CA group had significantly more disrupted and shallower nocturnal sleep than the other groups. On MSLT, the IHS w/o LST group had significantly longer sleep latency (SL) compared with the two NA groups. The latter two groups did not show statistical differences in diurnal variation of SL.ConclusionsThe IHS w/o LST group had milder objective daytime sleepiness compared with the NA groups. In patients with NA, nocturnal sleep disturbances appeared only in cases with CA, despite a similar trend in diurnal changes in sleep propensity between the two NA groups.SignificanceObjective nocturnal sleep disturbances are specific to NA patients with CA, whereas diurnal variations of sleep propensity are observed irrespective of the presence of CA among NA patients. These findings could be helpful for choosing optimal treatment plans for patients with these disorders.

► We compared indices of nocturnal polysomnography and diurnal variations in multiple sleep latency test parameters among patients with narcolepsy with and without cataplexy and idiopathic hypersomnia without long sleep time. ► Diurnal variations of sleep propensity are observed irrespective of the presence of cataplexy among narcolepsy patients, although objective nocturnal sleep disturbances are specific to narcolepsy patients with cataplexy. ► This study could be helpful for choosing optimal treatment plans for patients with these disorders.