Division of Sleep and Circadian Disorders, 221 Longwood Avenue, Boston, MA 02115, USA.
Scand J Work Environ Health. 2021 Jul 1;47(5):356-366. doi: 10.5271/sjweh.3953. Epub 2021 Mar 28.
Rotating shift work is associated with adverse outcomes due to circadian misalignment, sleep curtailment, work-family conflicts, and other factors. We tested a bright light countermeasure to enhance circadian adaptation on a counterclockwise rotation schedule.
Twenty-nine adults (aged 20-40 years; 15 women) participated in a 4-week laboratory simulation with weekly counterclockwise transitions from day, to night, to evening, to day shifts. Each week consisted of five 8-hour workdays including psychomotor vigilance tests, two days off, designated 8-hour sleep episodes every day, and an assessment of circadian melatonin secretion. Participants were randomized to a treatment group (N=14), receiving intermittent bright light during work designed to facilitate circadian adaptation, or a control group (N=15) working in indoor light. Adaptation was measured by how much of the melatonin secretion episode overlapped with scheduled sleep timing.
On the last night shift, there was a greater overlap between melatonin secretion and scheduled sleep time in the treatment group [mean 4.90, standard deviation (SD) 2.8 hours] compared to the control group (2.62, SD 2.8 hours; P=0.002), with night shift adaptation strongly influenced by baseline melatonin timing (r=-0.71, P=0.01). While the control group exhibited cognitive deficits on the last night shift, the treatment group's cognitive deficits on the last night and evening shifts were minimized.
In this laboratory setting, intermittent bright light during work hours enhanced adaptation to night work and subsequent readaptation to evening and day work. Light regimens scheduled to shift circadian timing should be tested in actual shift workers on counterclockwise schedules as a workplace intervention.
由于昼夜节律失调、睡眠不足、工作与家庭冲突等因素，轮班工作与不良后果相关。我们测试了一种强光对策，以增强逆时针旋转时间表上的昼夜适应能力。
29 名成年人（年龄 20-40 岁；15 名女性）参与了为期 4 周的实验室模拟，每周逆时针从白天、夜间、傍晚到白天过渡。每周包括 5 个 8 小时工作日，包括精神运动警觉测试、2 天休息日、每天指定 8 小时睡眠时间，并评估昼夜褪黑素分泌。参与者被随机分配到治疗组（N=14），接受间歇性强光照射，以促进昼夜适应，或对照组（N=15）在室内光线下工作。适应度通过褪黑素分泌期与预定睡眠时间的重叠程度来衡量。
在上夜班的最后一晚，治疗组（4.90 小时，SD 2.8 小时）的褪黑素分泌与预定睡眠时间的重叠程度明显大于对照组（2.62 小时，SD 2.8 小时；P=0.002），昼夜节律的基线褪黑素时间（r=-0.71，P=0.01）对夜间适应有强烈影响。虽然对照组在上夜班的最后一晚表现出认知缺陷，但治疗组在上夜班和傍晚班的认知缺陷最小化。
在这个实验室环境中，工作时间的间歇性强光增强了对夜班工作的适应，随后对傍晚和白天工作的适应也得到了增强。应根据实际倒班工人的情况，测试计划改变昼夜节律的光照方案，作为一种工作场所干预措施。
