Nighttime melatonin suppression is the most commonly used method to indirectly quantify acute nonvisual light effects. Since light is the principal zeitgeber in humans, there is a need to assess its strength during daytime as well. This is especially important since humans evolved under natural daylight but now often spend their time indoors under artificial light, resulting in a different quality and quantity of light. We tested whether the pupillary light response (PLR) could be used as a marker for nonvisual light effects during daytime. We also recorded the wake electroencephalogram to objectively determine changes in daytime sleepiness between different illuminance levels and/or spectral compositions of light. In total, 72 participants visited the laboratory 4 times for 3-h light exposures. All participants underwent a dim-light condition and either 3 metameric daytime light exposures with different spectral compositions of polychromatic white light (100 photopic lux, peak wavelengths at 435 nm or 480 nm, enriched with longer wavelengths of light) or 3 different illuminances (200, 600, and 1200 photopic lux) with 1 metameric lighting condition (peak wavelength at 435 nm or 480 nm; 24 participants each). The results show that the PLR was sensitive to both spectral differences between metameric lighting conditions and different illuminances in a dose-responsive manner, depending on melanopic irradiance. Objective sleepiness was significantly reduced, depending on melanopic irradiance, at low illuminance (100 lux) and showed fewer differences at higher illuminance. Since many people are exposed to such low illuminance for most of their day-living in biological darkness-our results imply that optimizing the light spectrum could be important to improve daytime alertness. Our results suggest the PLR as a noninvasive physiological marker for ambient light exposure effects during daytime. These findings may be applied to assess light-dependent zeitgeber strength and evaluate lighting improvements at workplaces, schools, hospitals, and homes.

中文翻译：

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生活在生物黑暗中：白天白天，不同的同色异谱照明条件会影响客观的嗜睡和瞳孔的光反应。

夜间褪黑激素抑制是间接量化急性非视觉光影响的最常用方法。由于光是人类的主要时代精神，因此也有必要在白天评估其强度。这一点尤其重要，因为人类是在自然光下进化的，但是现在人们经常在人造光下在室内度过时光，从而导致光的质量和数量不同。我们测试了瞳孔光反应（PLR）是否可以用作白天非视觉光影响的标记。我们还记录了唤醒脑波图，以客观地确定不同照度水平和/或光的光谱成分之间白天嗜睡的变化。总共有72名参与者4次访问了实验室3小时。所有参与者都处于昏暗的光线条件下，并进行了3次同色异谱的白天曝光，这些曝光具有不同的多色白光光谱成分（100照度勒克斯，峰值波长在435 nm或480 nm，富含更长的光波长）或3种不同的照度（200 ，600和1200照度lux）和1个同色异谱的光照条件（峰值波长在435 nm或480 nm；每个参与者24个）。结果表明，PLR对变色异构照明条件和不同照度之间的光谱差异均敏感，且剂量响应方式取决于黑素体辐照度。在低照度（100 lux）下，取决于黑素体辐照度，客观嗜睡性显着降低，而在较高照度下，客观嗜睡表现出较少的差异。由于许多人在生物黑暗中的大多数日常生活中都暴露在如此低的照度下，因此我们的结果表明优化光谱对提高白天的警觉性可能很重要。我们的结果表明，PLR可作为白天环境光暴露影响的一种非侵入性生理指标。这些发现可用于评估与光有关的Zeitgeber强度，并评估工作场所，学校，医院和家庭中的照明改善情况。