He Meiheng, Ru Taotao, Li Siyu, Li Yun, Zhou Guofu
Laboratory of Lighting and Physio-psychological Health, School of Psychology, South China Normal University, Guangzhou, China.
National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, China.
J Sleep Res. 2023 Apr;32(2):e13724. doi: 10.1111/jsr.13724. Epub 2022 Sep 4.
The relationship between daytime light, especially morning light and sleep, has not been well documented. People who work in an office spend most of their time indoors and thus have less access to high-level daylight. The current study employed a field intervention approach to investigate whether exposure to 1.5 h of bright electric light in the early morning for 1 workweek would benefit sleep among students who spent most of their time in an office at the university. Twelve students (24.92 ± 1.78 years) underwent a 2 workday baseline measurement and two inconsecutive 5 workday interventions (with 1 week washout) with morning bright light and regular office light (1000 lx, 6500 K vs. 300 lx, 4000 K, at eye level). The sleep outcomes were recorded with actigraphy and a sleep diary. In addition, self-ratings of daytime sleepiness, mood, mental fatigue, perceived effort, and next morning sleepiness were measured each workday. The results showed that exposure to morning bright light versus regular office light yielded a higher sleep efficiency (83.82% ± 1.60 vs. 80.35% ± 1.57, p = 0.02), a smaller fragmentation index (15.26% ± 1.31 vs. 17.18% ± 1.28, p = 0.05), and a shorter time in bed (7.12 ± 0.13 vs. 7.51 ± 0.12, p = 0.03). Meanwhile, an earlier sleep onset time, shorter sleep latency, and lower morning sleepiness were observed after a 5 workday morning bright light intervention compared with the baseline (ps <0.05), no such benefit was found for self-ratings (ps >0.05). These findings support existing evidence that morning bright light could function as an enhancer of sleep and alertness for office occupants.
白天的光线，尤其是早晨的光线与睡眠之间的关系尚未得到充分记录。在办公室工作的人大部分时间都在室内，因此接触高强度日光的机会较少。当前的研究采用现场干预方法，调查在大学办公室度过大部分时间的学生，在一周工作日的清晨暴露于1.5小时明亮的电灯下是否会对睡眠有益。12名学生（24.92±1.78岁）进行了为期2个工作日的基线测量，以及两次不连续的为期5个工作日的干预（有1周洗脱期），分别是早晨明亮灯光和常规办公室灯光（在眼睛水平处，1000勒克斯，6500开尔文与300勒克斯，4000开尔文）。使用活动记录仪和睡眠日记记录睡眠结果。此外，每个工作日测量白天嗜睡、情绪、精神疲劳、感知努力程度和次日早晨嗜睡的自我评分。结果显示，与常规办公室灯光相比，暴露于早晨明亮灯光下睡眠效率更高（83.82%±1.60对80.35%±1.57，p = 0.02），片段化指数更小（15.26%±1.31对17.18%±1.28，p = 0.05），卧床时间更短（7.12±0.13对7.51±0.12，p = 0.03）。同时，与基线相比，在为期5个工作日的早晨明亮灯光干预后，观察到入睡时间更早、睡眠潜伏期更短和早晨嗜睡程度更低（p值<0.05），自我评分方面未发现此类益处（p值>0.05）。这些发现支持了现有证据，即早晨明亮灯光可作为办公室人员睡眠和警觉性的增强剂。
