Abstract
We have been examining countermeasures to prevent sleepiness during boarding for train drivers. In the year before last, we had measured the environmental variables of a bedroom, which might negatively affect nocturnal sleep. On the basis of these results, we examined the effects of the illumination of the accommodations and nightclothes on nocturnal sleep. In the first experiment, the illumination equipment was changed from white fluorescent lamps to warm color fluorescent ones. In the second experiment, nightclothes were changed from traditional yukatas to other one-piece clothes. The results showed that the onset latency was reduced, and the sleep efficiency increased during nocturnal sleep after changing the illumination equipment. A subjective evaluation of nocturnal sleep showed an improvement when changing nightclothes.
