Faculty of Medicine and Health Sciences, McGill University, Montreal, QC, Canada.
Department of Psychology, Université du Québec à Montréal, Montreal, QC, Canada.
Sleep Health. 2023 Jun;9(3):373-380. doi: 10.1016/j.sleh.2023.02.004. Epub 2023 Apr 18.
Shift work causes circadian rhythms to misalign with the demands of the environment, which has been associated with sleep difficulties and cognitive impairments. Although bright light exposure during night shifts can improve circadian alignment, its implementation is often infeasible. Here, we tested whether light exposure in the evening, before the night shift, could improve fatigue, work performance, mood, and sleep.
Fifty-seven healthy nurses who worked full-time rapidly rotating shift schedules completed the study. In a mixed-design randomized controlled trial, participants completed a baseline observation period before following 1 of 2 interventions. The experimental intervention aimed to improve circadian alignment using evening light exposure and morning light avoidance; the control intervention aimed to improve alertness and reduce sleep disturbances by modifying diet. Every morning and evening for 30 days, participants completed measures of fatigue, work-related errors, sleepiness, mood, sleep duration, and sleep quality.
Compared to the baseline observation period, the experimental intervention reduced errors by 67%, while the control intervention reduced them by only 5%. This reduction was partially mediated by fatigue; experimental participants reported less fatigue on work days than control participants (d = 0.25 [0.10, 0.38]). The experimental group also showed a small improvement in mood. Both groups showed reductions in fatigue (d = 0.29 [0.20, 0.36]) and sleepiness (d = 0.21 [0.12, 0.28]) as well as a small increase in sleep duration.
Interventions based on evening light may be a feasible and effective strategy to reduce fatigue and errors in night-shift workers.
轮班工作导致昼夜节律与环境需求不匹配，从而导致睡眠困难和认知障碍。虽然夜间轮班时暴露在亮光下可以改善昼夜节律的调整，但实施起来往往不可行。在这里，我们测试了在夜班前的晚上进行光照是否可以改善疲劳、工作表现、情绪和睡眠。
57 名全职轮班工作的健康护士完成了这项研究。在一项混合设计的随机对照试验中，参与者在进行 2 种干预中的 1 种之前完成了基线观察期。实验组的干预目的是通过晚上光照和早上避免光照来改善昼夜节律的调整；对照组的干预目的是通过改变饮食来提高警觉性和减少睡眠障碍。在 30 天的时间里，参与者每天早晚完成疲劳、与工作相关的错误、困意、情绪、睡眠时间和睡眠质量的测量。
与基线观察期相比，实验组的错误减少了 67%，而对照组仅减少了 5%。这种减少部分是通过疲劳来介导的；实验组在工作日的疲劳感比对照组低（d=0.25[0.10,0.38]）。实验组的情绪也略有改善。两组都减少了疲劳感（d=0.29[0.20,0.36]）和困意（d=0.21[0.12,0.28]），睡眠时间也略有增加。
基于晚上光照的干预措施可能是减少夜间轮班工人疲劳和错误的一种可行且有效的策略。
