DAILY SLEEP CHANGES IN A NOISY ENVIRONMENT ASSESSED BY SUBJECTIVE AND POLYGRAPHIC SLEEP PARAMETERS

Abstract

Habituation of sleep to a noisy environment was investigated by self-rated sleep scores, polygraphic sleep parameters, and a performance test on the following morning. The self-rated sleep questionaire, OSA, includes five factors of subjective sleep quality: sleepiness, sleep maintenance, worry, integrated sleep feeling and sleep initiation. The polygraphic sleep parameters were six sleep stages in minutes, sleep latency, REM latency, REM cycle, REM duration, frequency and duration in minutes of awakening during sleep, total sleep time, number of sleep stage shifts, sleep efficiency, number of sleep spindles and density. The differences between reaction times before sleep that night and the following morning were also examined. The subjects were twelve students aged 19 to 21 who were tested a total of 96 nights. Each subject slept in an experimental room and was exposed to recorded passing truck noise with peak levels of 45, 50, 55 and 60 dB(A) at intervals of 15 min. Significant changes were recognized in Stage 1, MT, frequency of awakening and number of sleep stage shifts. The authors speculate that the decrease in the shallow stage as noisy nights were repeated reflects habituation of night sleep to repeated passing truck noise, whose interval, duration and nature was constant.