Alpha-delta sleep in a case with non-24 h sleep-wake syndrome: quantitative electroencephalogram analysis of alpha and delta band waves.

Four all-night polysomnograms of a 39-year-old male patient with non-24 h sleep-wake syndrome were recorded. We analysed electroencephalograms (EEG) with the power spectrum method and the wave pattern recognition analysis of Fujimori. The EEG of the rest waking condition showed normal patterns. High-voltage diffuse alpha band waves were observed in sleep stages 2, 3 and 4. The integrated area of the alpha band waves in the analysis epochs showed a strong positive correlation to the delta band components in the power spectrum of the same epoch during sleep (correlation coefficients r = 0.762-0.815). Alpha band waves during sleep were clearly different from the alpha waves in the rest waking condition, with respect to slower peak frequency and the frontal dominant voltage distribution.