Hakola T, Härmä M I, Laitinen J T
Department of Physiology, Finnish Institute of Occupational Health, Vantaa, Finland.
Scand J Work Environ Health. 1996 Apr;22(2):133-8. doi: 10.5271/sjweh.121.
The aims of the present study were to define the adjustment of sleep-wakefulness and other circadian rhythms during consecutive night shifts and to study the effect of gender on the adjustment to night work.
Twenty experienced shift workers, 9 men and 11 women, were studied under controlled laboratory conditions. After a night of habituation, the subjects worked one day shift and three night shifts. Rectal temperature was measured continuously during the study. Salivary melatonin and cortisol were assessed at 2-h intervals, and subjective sleepiness was checked every hour during the work shifts. Sleep was registered by the static-charge sensitive bed (SCSB) method after the workshifts.
Subjective sleepiness varied both between the work shifts and between the men and women. The subjects felt most alert during the day shift and were the sleepiest during the first night shift. Sleepiness decreased during the consecutive night shifts but did not reach the level of the day shift during the three nights. The sleepiness of the women decreased more than that of the men, the difference being significant during the second and third night shifts (P < 0.05). The circadian rhythm of body temperature, salivary cortisol, and time in bed changed significantly (P < 0.05) between the workshifts, but no differences were found between the men and women in the circadian adjustment of the physiological variables to night work.
The men felt sleepier than the women during the consecutive night shifts, although no physiological differences were found between the genders. However, since normal social and domestic factors were excluded, the findings cannot be considered as evidence of women's better adaptation to night work in everyday life.
本研究的目的是确定连续夜班期间睡眠-觉醒及其他昼夜节律的调整情况，并研究性别对夜班适应的影响。
在可控的实验室条件下，对20名经验丰富的轮班工人进行了研究，其中男性9名，女性11名。经过一晚的适应后，受试者先上一个日班，然后连续上三个夜班。研究期间持续测量直肠温度。每隔2小时评估唾液褪黑素和皮质醇水平，并且在工作期间每小时检查主观嗜睡程度。下班后通过静电荷敏感床（SCSB）方法记录睡眠情况。
主观嗜睡程度在不同班次之间以及男女之间均有所不同。受试者在日班期间感觉最警觉，而在第一个夜班期间最困倦。在连续夜班期间嗜睡程度有所下降，但在三个晚上期间均未达到日班时的水平。女性的嗜睡程度下降幅度大于男性，在第二个和第三个夜班期间差异显著（P<0.05）。体温、唾液皮质醇和卧床时间的昼夜节律在不同班次之间有显著变化（P<0.05），但在生理变量对夜班的昼夜调整方面，男女之间未发现差异。
在连续夜班期间，男性比女性感觉更困倦，尽管男女之间未发现生理差异。然而，由于排除了正常的社会和家庭因素，这些发现不能被视为女性在日常生活中更能适应夜班工作的证据。
