P. Philip et al., SLEEP FRAGMENTATION IN NORMALS - A MODEL FOR SLEEPINESS ASSOCIATED WITH UPPER AIRWAY-RESISTANCE SYNDROME, Sleep, 17(3), 1994, pp. 242-247
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.