Zerbini Giulia, Kantermann Thomas, Merrow Martha
Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands.
Institute of Medical Psychology, LMU Munich, Munich, Germany.
Eur J Neurosci. 2020 Jun;51(12):2355-2366. doi: 10.1111/ejn.14293. Epub 2018 Dec 13.
The timing of sleep is under the control of the circadian clock, which uses light to entrain to the external light-dark cycle. A combination of genetic, physiological and environmental factors produces individual differences in chronotype (entrained phase as manifest in sleep timing). A mismatch between circadian and societal (e.g., work) clocks leads to a condition called social jetlag, which is characterized by changing sleep times over work and free days and accumulation of sleep debt. Social jetlag, which is prevalent in late chronotypes, has been related to several health issues. One way to reduce social jetlag would be to advance the circadian clock via modifications of the light environment. We thus performed two intervention field studies to describe methods for decreasing social jetlag. One study decreased evening light exposure (via blue-light-blocking glasses) and the other used increased morning light (via the use of curtains). We measured behaviour as well as melatonin; the latter in order to validate that behaviour was consistent with this neuroendocrinological phase marker of the circadian clock. We found that a decrease in evening blue light exposure led to an advance in melatonin and sleep onset on workdays. Increased morning light exposure advanced neither melatonin secretion nor sleep timing. Neither protocol led to a significant change in social jetlag. Despite this, our findings show that controlling light exposure at home can be effective in advancing melatonin secretion and sleep, thereby helping late chronotypes to better cope with early social schedules.
睡眠时机受昼夜节律时钟控制，昼夜节律时钟利用光线与外部昼夜明暗周期同步。遗传、生理和环境因素共同作用，导致个体在生物钟类型（在睡眠时间表现出的同步相位）上存在差异。昼夜节律时钟与社会（如工作）时钟不匹配会导致一种称为社会时差的状况，其特征是工作日和休息日的睡眠时间变化以及睡眠债的累积。社会时差在晚睡型人群中很普遍，与多种健康问题有关。减少社会时差的一种方法是通过改变光照环境来提前昼夜节律时钟。因此，我们进行了两项干预性实地研究，以描述减少社会时差的方法。一项研究减少了夜间光照暴露（通过佩戴防蓝光眼镜），另一项研究增加了早晨光照（通过使用窗帘）。我们测量了行为以及褪黑素；测量褪黑素是为了验证行为是否与昼夜节律时钟的这种神经内分泌相位标记一致。我们发现，减少夜间蓝光暴露会使工作日的褪黑素分泌提前和入睡时间提前。增加早晨光照暴露既没有提前褪黑素分泌，也没有提前睡眠时间。两种方案都没有导致社会时差发生显著变化。尽管如此，我们的研究结果表明，在家中控制光照暴露可以有效地提前褪黑素分泌和睡眠时间，从而帮助晚睡型人群更好地应对早期的社会日程安排。
