AUTONOMIC FUNCTION IN NARCOLEPSY - POWER SPECTRUM ANALYSIS OF HEART-RATE-VARIABILITY

Ten narcoleptic patients that had never been treated previously and te n healthy volunteers of comparable age underwent 48-h polygraphic reco rding to assess the effects of wakefulness and sleep on beat-to-beat h eart rate variability by means of power spectrum analysis. The study r evealed decreased power in the low frequencies (LF) during sleep (wher eby an increase of the power in this band is associated with sympathet ic activation) compared with wakefulness, with minimal values during s tage 3-4 non-REM sleep and higher levels during REM sleep, both in pat ients and controls. Significantly reduced power in high frequencies (H F; mainly expression of parasympathetic control) and a significantly i ncreased LF/HF ratio during wakefulness before sleep in narcoleptics c ompared with controls were found, Our study excludes a primary disturb ance of cardiac autonomic nervous system in narcoleptics but suggests an altered circadian autonomic function in these patients.