Influence of lateral motion transfer on sleep

This study examined the effects of motion of an artificial bed partner on t he sleep of a real subject on the same mattress. A 240-lb eight-sided cylin drical roller served as the artificial bed partner. The roller was placed o n one side of a king-size mattress and a normal adult slept on the other ha lf. On experimental nights, the roller intermittently rocked back and forth for brief periods of time which in aggregate represented approximately 13% of total sleep time. On control nights, the roller was stationary. After a n adaptation night in the laboratory, subjects spent two more nights in the sleep laboratory. The order of Roller On and Roller Off nights was random. 24 subjects were randomly assigned to sleep on one of the three surfaces. The three mattresses used in the study had different construction designs a nd in turn variable properties of motion transfer. Sleep variables were mea sured objectively by nocturnal polysomnography and subjectively by a postsl eep questionnaire. Analysis of the data indicated that motion transferred l aterally across a mattress was associated with a significant increase in St age 1 sleep, and a significant decrease in Stage 3/4 sleep. Over-all, sleep efficiency, number of awakenings, and wakefulness after sleep onset did no t show significant changes from control to experimental nights. The amount of change in sleep architecture, however, mas more notable on the mattresse s which transferred more motion. An implication of these findings is that m otion transferred across the surface of a mattress, by lightening the depth of sleep and thereby decreasing the auditory arousal threshold, can increa se the potential for sleep disruption from environmental stimuli such as no ise.