DIFFERENTIAL-EFFECTS OF EXTENDED SLEEP IN NARCOLEPTIC PATIENTS

The aim of the present study was to investigate the effects of extende d night sleep on subsequent daytime sleep propensity in narcoleptic pa tients. The possible differentiation between REM and NREM sleepiness w as of particular interest. Ten unmedicated narcoleptic inpatients (8 m en, 2 women) aged 23-61 years (mean, 47.9 years) participated in this study. Adapting the patients to the hospital schedule (nocturnal sleep period from 22:00 to 6:00 h and ad lib. nap Juring daytime) for at le ast 2 weeks, we conducted a baseline PSG from 22:00 to 6:00 h and subs equent 5-trial daytime sleep recordings with naps (lying on the bed fo r 20 min light-out period) at 9:30, 11:30, 13:30, 15:30 and 17:30 h (t he baseline condition: BC). After a 1-5 day interval, we conducted an extended PSG from 22:00 to 10:00 h. Subsequent to the extended PSG, we carried out 5-trial daytime sleep recordings. We adjusted the start t ime of the first nap trial at least 90 min after waking time and start time of the 5th nap trial before 19:00 h (the extended condition: EC) . Mean TST was 417.0 min in the baseline PSG, and 595.2 min in extende d PSG. Mean number of daytime naps pet. subject exhibiting a sleep lat ency shorter than 10 min was decreased in EC. Mean sleep latency in EC was significantly prolonged in comparison with that in BC. This prolo ngation of mean sleep latency per subject was positively correlated wi th S4 duration and % S4 obtained in the morning of the extended PSG (f rom 6:00 to wake time). Mean number of nap trials containing a REM epi sode in EC did not differ significantly from that in BC. Mean REM late ncy per subject was not significantly different. There was no signific ant difference with respect to sequential distribution of REM containi ng naps. In this study, daytime sleep propensity in narcoleptic patien ts was partially reduced by nocturnal sleep extension, while daytime R EM sleep propensity was not affected. These results could support the possibility that an appropriate nocturnal sleep extension is helpful f or narcoleptic patients in reducing excessive daytime sleepiness.