Biological rhythm and womens's night-shift work : an occupational and physiological study of effects and mechanisms.

本研究试图：1）建立一种新的非线性生理数据时间序列分析方法; 2）从行为医学的角度阐明女性夜班工作的环境、职业和心理社会因素之间的关系; 3）阐明女性夜班工作对心血管系统生物节律的影响及其机制。采用最大熵功率谱分析和最小二乘法对24 h以上的血压和心率等生理时间序列数据进行周期结构提取和最佳拟合曲线拟合。由于原始数据与最佳拟合曲线之间的残差及其标准差仅为10^<-8>至10^<-9>不等，因此这种使用人工周期函数的分析方法对于定量评估生物节律的变化非常有效。在工作结束时的主观疲劳症状，以及从15或30分钟间隔测量的血压的时间序列数据中提取的每个阶段（6或7小时），对于白班和夜班工人是相似的。然而，在连续夜间工作后的白天，观察到伴随着血压和心率增加的中间觉醒的睡眠。除了睡眠不足之外，被称为日常压力的心理因素也可能影响生物节律。由此可见，夜班睡眠和减少日常压力对维持生物节律是有效的。此外，尽管夜班工作对男女生物节律变化的影响没有得到澄清，但建议在职业领域进行卫生管理，特别是在劳动部最近允许妇女从事夜班工作的过程中。

This study attempted 1) to establish a new method of time-series analysis for nonlinear physiological data , 2) to clarify the relationships between environmental, occupational and psycho-social factors of women's night-shift work utilizing a behavioral-medical approach, and 3) to elucidate the effects and their mechanisms on biological rhythm in the cardio-vascular system. Maximum entropy power spectral analysis and the least square method were performed to extract the periodic structure and the best fitting curves from physiological time-series data including blood pressure and heart rate recorded longer than 24 hours. As the residuals and their standard deviations between the raw data and the best fitting curves varied from only 10^<-8> to 10^<-9>, this method of analysis using artificial periodic functions is very effective to quantitatively evaluate changes of biological rhythm. Subjective fatigue symptoms at the end of work, and each phase (6 or 7 hours) of periods extracted from time-series data of blood pressure measured at 15 or 30 minutes interval, were similar for day- and nightshift workers. However, in the daytime after continuous night work, sleep with intermediate arousal accompanied by an increase in blood pressure and heart rate were observed. Psychological factors referred to as daily stress in addition to insufficient sleep may possibly have affected the biological rhythm. From the above, it is suggested that sleep in night-shift work and the reduction of daily stress are effective to maintain biological rhythm. Further, although the sexual differences of changes in biological rhythm by night-shift work were not clarified, the importance of health administration in the occupational fields is suggested, particulary in the recent process of the Ministry of Labor giving access to women to night-shift work.