Studies on the night work and shift of guards. Part 2. Effects of prolonged on-duty and overtime work on daily activities and sleeping hours (author's transl)

Abstract

For the purpose of clarifying the effect of night and shift work on daily lives of workers, hours for daily activities and sleeping hours of guardmen were investigated during a week and a month, respectively. The subjects included 36 alternate-day shift workers, aged 37.0±12.4 years on the average, 6 permanent night duty workers, aged 53.8±3.7 years, and 6 normal duty workers, aged 41.8±10.5years. The characteristics of each duty have been described in the previous report. The results were as follows: (1) The investigation of daily life hours during a week showed that the daily working hours including commuting hours averaged 831 min, 970 min, and 568 min, for the alternate-day shift workers, for the permanent night duty workers, and for the normal duty workers, respectively. Therefore the former two were longer than the last, showing about 60% of the daily life hours. In contrast, their sleeping and socio-cultural hours were shortened, and these hours were revealed to be more shortened by longer working hours. (2) The frequency of sleeping times in one-month was 40 and 59, for the alternate-day shift workers and for the permanent night workers, both being significantly greater than 31 for the normal duty workers. The frequency of sleeping times at home was 16 for the alternate-day shift workers, while only 4 for the permanent workers. These results indicate both shift workers had very few chances to have a good sleep at home. (3) The average sleeping hours for a month was 6.9 hr in a day for the alternate-day shift workers and 7.0 hr for the permanent night workers, while 8.1 hr for the normal duty workers. This result indicates that the shift workers were obliged to have insufficient sleep for a month, compared with the normal duty workers. The insufficient sleep were suggested to be caused by such factors as consecutive night duties, short interval between duties, long spell of portal-to-portal hours and high freguency of night works. (4) It was observed that extremely insufficient sleep of the shift workers, which was brought about by successive duties, may be compensated, although a little, by full night sleep before and after the duties as well as by taking a good diurnal sleep. There were also shown clear individual differences with regard to how to compensate the sleep loss. It was concluded from these results that countermeasures such as shortening of total and overtime working hours, decrease in frequency of night duties as well as increase in frequency of off-duty days should be urgently taken, in order to make sure of guardmen's full sleep and to improve their health, from the viewpoint of industrial hygiene.