Panagiotou Maria, Rohling Jos H T, Deboer Tom
Laboratory for Neurophysiology, Department of Cell and Chemical Biology, Leiden University Medical Centre, 2300 Leiden, The Netherlands;
Clocks Sleep. 2020 Jul 23;2(3):308-324. doi: 10.3390/clockssleep2030023. eCollection 2020 Sep.
Artificial light, despite its widespread and valuable use, has been associated with deterioration of health and well-being, including altered circadian timing and sleep disturbances, particularly in nocturnal exposure. Recent findings from our lab reveal significant sleep and sleep electroencephalogram (EEG) changes owing to three months exposure to dim-light-at-night (DLAN). Aiming to further explore the detrimental effects of DLAN exposure, in the present study, we continuously recorded sleep EEG and the electromyogram for baseline 24-h and following 6-h sleep deprivation in a varied DLAN duration scheme. C57BL/6J mice were exposed to a 12:12 h light:DLAN cycle (75lux:5lux) vs. a 12:12 h light:dark cycle (75lux:0lux) for one day, one week, and one month. Our results show that sleep was already affected by a mere day of DLAN exposure with additional complications emerging with increasing DLAN exposure duration, such as the gradual delay of the daily 24-h vigilance state rhythms. We conducted detrended fluctuation analysis (DFA) on the locomotor activity data following 1-month and 3-month DLAN exposure, and a significantly less healthy rest-activity pattern, based on the decreased alpha values, was found in both conditions compared to the control light-dark. Taking into account the behavioral, sleep and the sleep EEG parameters, our data suggest that DLAN exposure, even in the shortest duration, induces deleterious effects; nevertheless, potential compensatory mechanisms render the organism partly adjustable and able to cope. We think that, for this reason, our data do not always depict linear divergence among groups, as compared with control conditions. Chronic DLAN exposure impacts the sleep regulatory system, but also brain integrity, diminishing its adaptability and reactivity, especially apparent in the sleep EEG alterations and particular low alpha values following DFA.
人造光尽管有着广泛且重要的用途，但却与健康和幸福感的下降有关，包括昼夜节律紊乱和睡眠障碍，尤其是在夜间接触人造光的情况下。我们实验室最近的研究结果显示，由于连续三个月暴露于夜间昏暗灯光（DLAN）下，睡眠和睡眠脑电图（EEG）出现了显著变化。为了进一步探究DLAN暴露的有害影响，在本研究中，我们采用不同的DLAN持续时间方案，连续记录了基线24小时以及随后6小时睡眠剥夺期间的睡眠EEG和肌电图。将C57BL/6J小鼠暴露于12:12小时光照:DLAN循环（75勒克斯:5勒克斯）与12:12小时光照:黑暗循环（75勒克斯:0勒克斯）中，分别持续一天、一周和一个月。我们的结果表明，仅仅一天的DLAN暴露就已经对睡眠产生了影响，并且随着DLAN暴露持续时间的增加，还会出现更多并发症，例如每日24小时警觉状态节律的逐渐延迟。我们对暴露于DLAN 1个月和3个月后的运动活动数据进行了去趋势波动分析（DFA），结果发现，与对照的明暗循环相比，在这两种情况下，基于α值降低，休息-活动模式的健康程度显著降低。综合行为、睡眠和睡眠EEG参数来看，我们的数据表明，即使是最短时间的DLAN暴露也会产生有害影响；然而，潜在的补偿机制使机体具有一定的适应性并能够应对。我们认为，正因如此，与对照条件相比，我们的数据并不总是呈现出各组之间的线性差异。长期暴露于DLAN会影响睡眠调节系统，还会损害大脑完整性，降低其适应性和反应性，这在睡眠EEG改变以及DFA后特别低的α值中尤为明显。
