EFFECTS OF TEMPORARILY LIMITED NOISE CALMING PERIODS DURING SLEEP

摘要

As traffic density will increase in the forthcoming years, more during the shoulder hours and during the night than during the day and due to the deleterious effects of noise on sleep this paper evaluates 3 models of temporary quiet periods during the night. As the times of these periods are oriented to the sleep behaviour of the majority of the adult population persons with different bedtimes are concerned. Twenty-four healthy young persons (12 women, 12 men, 21 - 27 yrs) slept in 2 consecutive weeks, four nights each week in the laboratory while during one week each exposed to road or railway noises. Three models of temporary quiet periods were realized: two starting at 11 pm and lasting 4 or 6 hours and one starting at 3 am and lasting until 7 am. Eight normal sleepers went to bed at 11 pm, eight early sleepers at 10 pm and eight late sleepers at 12 pm, wake-up call was eight hours later. The overall 9 exposure patterns were reduced to three main exposure patterns, defined by the quiet period in the beginning, in the middle or at the end of the subjective night. During all nights polysomnograms were recorded continuously, sleep was evaluated subjectively every morning. Noise in the beginning of the night caused disturbances before and shortly after noise onset. If the night is terminated by a quiet period only, the initial disturbances are fully compensated. However, whenever the subjective night is terminated with an even short noise period, sleep structure and subjective evaluation of sleep are significantly impaired. Thus, whenever a temporary quiet period during the night is considered, it is strongly recommended to locate this period at the end of the subjective night. In any case late sleepers profit less from such regulations.