EEG spectral analysis of the sleep-onset period in narcoleptics and normalsleepers

The sleep-onset period of 10 drug-free patients with narcolepsy-cataplexy a nd 10 normals matched for age and gender was investigated using the multipl e sleep latency test to elicit episodes of intentional sleep onset. Spectra l analyses were calculated for delta, theta, alpha, sigma, and beta frequen cies using 5-second epochs beginning at lights-out and continuing until the first 2 minutes of stage 2 or REM sleep were reached, or until 20 minutes had elapsed. The sleep-onset period was divided into quartiles, and mean ro ot mean square (RMS) amplitude within each quartile was calculated. Mean de lta amplitude was significantly higher across the sleep-onset period of nar coleptic REM naps and narcoleptic stage 2 naps compared to the sleep-onset period of normal stage 2 naps or normal stage 1 naps. Mean theta amplitude was significantly higher for narcoleptic REM naps compared to normal stage 1 naps, and tended to be higher for narcoleptic stage 2 naps compared to no rmal stage 1 naps. Mean alpha amplitude was significantly lower for narcole ptic REM naps and narcoleptic stage 2 naps compared to normal naps containi ng just stage 1. Mean sigma amplitude was significantly lower for narcolept ic REM naps compared to normal stage 1 naps, and tended to be lower for nar coleptic REM naps compared to normal stage 2 naps. Mean beta amplitude did not differ between the narcoleptic and normal sleep-onset process. These fi ndings support the existence of electrophysiologic differences within the m icrostructure of the process of sleep entry in narcoleptics and normals.