Surrey Sleep Research Centre, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK.
J Pineal Res. 2012 Aug;53(1):47-59. doi: 10.1111/j.1600-079X.2011.00970.x. Epub 2011 Oct 24.
The effect of light on circadian rhythms and sleep is mediated by a multi-component photoreceptive system of rods, cones and melanopsin-expressing intrinsically photosensitive retinal ganglion cells. The intensity and spectral sensitivity characteristics of this system are to be fully determined. Whether the intensity and spectral composition of light exposure at home in the evening is such that it delays circadian rhythms and sleep also remains to be established. We monitored light exposure at home during 6-8wk and assessed light effects on sleep and circadian rhythms in the laboratory. Twenty-two women and men (23.1±4.7yr) participated in a six-way, cross-over design using polychromatic light conditions relevant to the light exposure at home, but with reduced, intermediate or enhanced efficacy with respect to the photopic and melanopsin systems. The evening rise of melatonin, sleepiness and EEG-assessed sleep onset varied significantly (P<0.01) across the light conditions, and these effects appeared to be largely mediated by the melanopsin, rather than the photopic system. Moreover, there were individual differences in the sensitivity to the disruptive effect of light on melatonin, which were robust against experimental manipulations (intra-class correlation=0.44). The data show that light at home in the evening affects circadian physiology and imply that the spectral composition of artificial light can be modified to minimize this disruptive effect on sleep and circadian rhythms. These findings have implications for our understanding of the contribution of artificial light exposure to sleep and circadian rhythm disorders such as delayed sleep phase disorder.
光对昼夜节律和睡眠的影响是由多组分光感受器系统介导的，该系统由视杆细胞、视锥细胞和表达黑视蛋白的固有光敏感视网膜神经节细胞组成。该系统的强度和光谱灵敏度特征有待完全确定。晚上在家中暴露于光的强度和光谱组成是否会延迟昼夜节律和睡眠，这也有待确定。我们监测了 6-8 周内在家中的光暴露情况，并在实验室中评估了光对睡眠和昼夜节律的影响。22 名女性和男性（23.1±4.7 岁）参与了一项六向交叉设计，使用与在家中光暴露相关的多色光条件，但与光系统和黑视蛋白系统相比，光的效能降低、中等或增强。褪黑素、困倦和 EEG 评估的睡眠起始的夜间上升在不同的光照条件下差异显著（P<0.01），这些影响似乎主要是由黑视蛋白介导的，而不是光系统介导的。此外，对光对褪黑素的破坏作用的敏感性存在个体差异，这些差异对实验操作具有稳健性（组内相关系数=0.44）。这些数据表明，晚上在家中的光会影响昼夜生理，并且暗示可以修改人工光的光谱组成，以最小化其对睡眠和昼夜节律的破坏作用。这些发现对我们理解人工光暴露对睡眠和昼夜节律障碍（如睡眠时相延迟障碍）的贡献具有重要意义。
