Objective: To determine whether the spectral activity during sleep of patie
nts with idiopathic hypersomnia (IH) differs from that of healthy subjects.
Methods: Spectral analysis of the electroencephalogram (EEC;) was performed
: in 10 patients with IH and in 10 age-matched control subjects. We compare
d the time course of absolute power for slow wave activity (SWA: 0.75-4.5 H
z), and for theta, alpha, sigma and beta bands for the first 4 non-rapid-ey
e movement (NREM) episodes.
Results: Compared to controls, IH patients had less SWA across the night al
though the exponential decay was preserved. The fall in SWA was statistical
ly significant for the first two NREM episodes only. The lower power of SWA
was related to lower amounts of stages 3 and 4 of NREM sleep during the sl
eep episodes. No correlation was found between SWA during the night and the
mean sleep latency on the multiple sleep latency test (MSLT).
Conclusions: These results showed that, in IH patients, the homeostatic sle
ep regulatory mechanisms are preserved but the sleep pressure, indicated by
SWA, is lower. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.