Analysis of sleep fragmentation and sleep structure in patients with sleep apnea and normal volunteers.

Sleep disorders have a high prevalence. Sleep disorders are recognized first by the complaint of nonrestorative sleep. A quantification of the disorder is done by the investigation in a sleep laboratory. The investigation in the sleep laboratory examines the EEG, EOG and EMG to derive sleep stages. This is a labor intensive sleep scoring after the polysomnography investigation. Usually the time course of the sleep stages is quantified in terms of percentages of stages related to total sleep time and the latencies for the individual stages. The additional feature of transitions between sleep stages and the disruption of sleep, which corresponds to periods of wakefulness during sleep are not evaluated systematically. We have evaluated these transitions using a statistical approach. We have detected systematic differences in the distributions o sleep stages and wake states during sleep. This differences were investigates in normal subjects and patients with sleep apnea. Then these differences were investigated in different species. The difference in the distributions can be explained only by fundamentally different regulation of sleep and wakefulness.