Increased REM density in narcolepsy-cataplexy and the polysymptomatic formof idiopathic hypersomnia

The present work is focused on REM sleep density in patients with primary h ypersomnia in comparison with non-hypersomnia subjects. 28 unmedicated pati ents with narcolepsy-cataplexy (NC) and 10 unmedicated patients suffering f rom the polysymptomatic form of idiopathic hypersomnia (IH) and their age- and sex-matched controls were included in the study, The clinical diagnosis was confirmed by MSLT and nocturnal PSG, HLA typing was performed in a res pective group of narcoleptic patients. Polygraphical recordings were visual ly scored with particular regard to the two most characteristic phasic feat ures of REM sleep: the number of rapid eye movements (REMs) and chin muscle twitches (Tws) per minute. These events were evaluated according to recogn ized criteria; a closer look was taken at both their frequency and their di stribution across all the nocturnal REM periods (REMPs). The following main differences between hypersomniac patients (of both groups examined) and he althy controls were found in terms of phasic activity: (I) REM density (exp ressed in REMs/min and Tws/min in each REM period) was significantly increa sed in the hypersomniac patients in comparison with the controls. (p>0.05). (II) The intra-night phasic activity distribution was found rising more con spicuously in the hypersomniacs than in the controls.