SLEEP FRAGMENTATION IN NORMALS - A MODEL FOR SLEEPINESS ASSOCIATED WITH UPPER AIRWAY-RESISTANCE SYNDROME

Eight young adults underwent 1 night of auditory sleep fragmentation f ollowed by four naps of the multiple sleep latency test and performanc e testing the next day. A latin-square design was used to compare resu lts with baseline. Efforts were made to eliminate effects of learning on repeated performance tests. A mean of 303 arousals, lasting a mean of 11 seconds, disrupted nocturnal sleep. This sleep fragmentation was induced to mimic as closely as possible the nocturnal sleep disruptio n seen in subjects with upper airway resistance syndrome. There was a significant disruption of nocturnal sleep architecture with a signific ant overall decrease in slow-wave sleep (SWS) and a significant but mo re moderate decrease in rapid eye movement (REM) sleep during the frag mented night. The most interesting finding related to analysis by thir ds of the night, which indicated an important increase over time in ar ousal threshold during SWS followed by REM sleep. This threshold incre ase was associated with a parallel increase in dB(A) levels needed to induce an arousal. Stages 1 and 2 nonrapid eye movement (NREM) sleep w ere less affected by the stimulation, but the amount of stage 1 NREM s leep decreased from the beginning to the end of the night, again indic ating an increase in pressure to sleep. Following 1 night of sleep fra gmentation, subjects had significantly shorter sleep latencies on the multiple sleep latency test for naps 2, 3 and 4. There was a significa nt relationship between percent nocturnal SWS and mean sleep latencies . The selected performance tests were not affected by 1 night of sleep fragmentation, despite the obvious sleepiness.