Centre for Biological Timing, Faculty of Biology, Medicine & Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
Centre for Biological Timing, Faculty of Biology, Medicine & Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
Curr Biol. 2019 Dec 16;29(24):4260-4267.e4. doi: 10.1016/j.cub.2019.10.028.
In humans, short-wavelength light evokes larger circadian responses than longer wavelengths [1-3]. This reflects the fact that melanopsin, a key contributor to circadian assessments of light intensity, most efficiently captures photons around 480 nm [4-8] and gives rise to the popular view that "blue" light exerts the strongest effects on the clock. However, in the natural world, there is often no direct correlation between perceived color (as reported by the cone-based visual system) and melanopsin excitation. Accordingly, although the mammalian clock does receive cone-based chromatic signals [9], the influence of color on circadian responses to light remains unclear. Here, we define the nature and functional significance of chromatic influences on the mouse circadian system. Using polychromatic lighting and mice with altered cone spectral sensitivity (Opn1mw), we generate conditions that differ in color (i.e., ratio of L- to S-cone opsin activation) while providing identical melanopsin and rod activation. When biased toward S-opsin activation (appearing "blue"), these stimuli reliably produce weaker circadian behavioral responses than those favoring L-opsin ("yellow"). This influence of color (which is absent in animals lacking cone phototransduction; Cnga3) aligns with natural changes in spectral composition over twilight, where decreasing solar angle is accompanied by a strong blue shift [9-11]. Accordingly, we find that naturalistic color changes support circadian alignment when environmental conditions render diurnal variations in light intensity weak/ambiguous sources of timing information. Our data thus establish how color contributes to circadian entrainment in mammals and provide important new insight to inform the design of lighting environments that benefit health.
在人类中，短波长光比长波长光引起更大的昼夜节律反应[1-3]。这反映了一个事实，即视黑质（melanopsin）是对光强度进行昼夜节律评估的关键贡献者，它最有效地捕获 480nm 左右的光子[4-8]，并产生了一个流行的观点，即“蓝光”对时钟的影响最强。然而，在自然界中，人们感知到的颜色（由视锥细胞视觉系统报告）与视黑质的兴奋之间通常没有直接的相关性。因此，尽管哺乳动物时钟确实接收基于视锥细胞的色觉信号[9]，但颜色对光的昼夜节律反应的影响仍不清楚。在这里，我们定义了颜色对小鼠昼夜节律系统的影响的性质和功能意义。我们使用多色照明和具有改变的视锥细胞光谱敏感性的小鼠（Opn1mw），生成了在颜色上不同的条件（即 L-视锥细胞和 S-视锥细胞 opsin 激活的比例），同时提供相同的视黑质和视杆细胞激活。当偏向于 S-opsin 激活（呈现“蓝色”）时，这些刺激比有利于 L-opsin（“黄色”）的刺激更可靠地产生较弱的昼夜节律行为反应。这种颜色的影响（在缺乏视锥细胞光转导的动物中不存在；Cnga3）与暮光期间光谱组成的自然变化一致，随着太阳角度的降低，出现强烈的蓝移[9-11]。因此，我们发现当环境条件使光强度的昼夜变化成为弱/模糊的时间信息来源时，自然的颜色变化会支持昼夜节律的对齐。我们的数据因此确定了颜色如何为哺乳动物的昼夜节律同步提供贡献，并为设计有利于健康的照明环境提供了重要的新见解。
