HABITUATION OF SLEEP TO A SHIPʹS NOISE AS DETERMINED BY ACTIGRAPHY AND A SLEEP QUESTIONNAIRE

Habituation of sleep to a shipʹs noise was assessed by actigraphy and a sleep questionnaire. Four male students aged 21–24 years were studied for 15 consecutive nights in an experimental bedroom. During the first four nights, the subjects slept in a quiet environment. For the next eight consecutive nights, the subjects were exposed to the noise of a shipʹs engine with a sound level of 60dB(A) (the International Maritime Organization Standard) previously tape-recorded in a room of a diesel engine ship. On the last three experimental nights, the subjects again slept in a quiet environment. The subjects went to bed in the experimental room at about 0:00 and were woken at 8:00 a.m. the next morning by an alarm clock. Sleep was monitored by a wrist-worn actigraphy. On the morning following each experimental night, the subjects were instructed to answer the OSA questionnaire, a structured self-rating sleep scale developed in Japan. Habituation of sleep to the noise of a ship with a sound level of 60dB(A) was observed to some extent in the subjective sleep parameters but not in the sleep parameters measured by actigraphy.