Artificial light at night (ALAN) has become a pervasive anthropogenic stressor for both humans and wildlife. Although many negative impacts of ALAN on human health have been identified, the consequences for infectious disease dynamics are largely unexplored. With the increase in popularity of energy efficient light-emitting diodes (LEDs), the effects of spectral composition of ALAN have also come into question. Previous studies showed that exposure to low levels of incandescent ALAN extended the infectious period of House Sparrows (Passer domesticus) infected with West Nile virus (WNV) without affecting mortality rates, thus increasing the pathogen initial reproductive rate (R₀) by ~41%. Here, we asked whether exposure to broad-spectrum (3000 K [Kelvin; unit of color temperature]) ALAN suppressed melatonin, a hormone implicated in ALAN-induced physiological consequences, in House Sparrows. We then asked whether amber-hue bulbs (1800 K) could ameliorate the effects of WNV on individual sparrows, and whether broad-spectrum or blue-rich bulbs (3000 K and 5000 K, respectively) could exacerbate them. We found that exposure to low intensity (~5 lux) broad-spectrum (3000 K) ALAN significantly suppressed melatonin levels throughout the night. Second, we found that exposure to broad-spectrum and blue-rich (3000 + 5000 K) lights did not affect WNV viremia but did increase WNV-induced mortality. Conversely, birds exposed to amber-hue (1800 K) ALAN had lower viremia and mortality rates similar to controls (i.e. natural light conditions). This study demonstrates that ALAN affects melatonin regulation in birds, but this effect, as well as ALAN influences on infectious disease responses, can be ameliorated by particular lighting technologies.

中文翻译：

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广谱光污染抑制褪黑激素并增加麻雀（Passer domesticus）中由西尼罗河病毒引起的死亡率

夜间人造光（ALAN）已成为人类和野生生物普遍的人为压力源。尽管已经确定了ALAN对人类健康的许多负面影响，但对于传染病动态的后果却很大程度上尚待探讨。随着高能效发光二极管（LED）的普及，ALAN光谱组成的影响也受到质疑。先前的研究表明，暴露于低水平的白炽ALAN会延长感染西尼罗河病毒（WNV）的麻雀（Passer domesticus）的感染期，而不会影响死亡率，从而提高了病原体的初始繁殖率（R ₀）〜41％。在这里，我们询问在麻雀中是否暴露于广谱（3000 K [开尔文；色温单位]）ALAN会抑制褪黑激素，褪黑激素是一种与ALAN引起的生理后果有关的激素。然后，我们询问琥珀色灯泡（1800 K）是否可以改善WNV对单个麻雀的影响，以及广谱灯泡或蓝蓝色灯泡（分别为3000 K和5000 K）是否会加剧它们。我们发现暴露于低强度（〜5 lux）广谱（3000 K）ALAN可以显着抑制通宵的褪黑激素水平。其次，我们发现暴露于广谱和蓝色丰富（3000 + 5000 K）的灯光下不会影响WNV病毒血症，但会增加WNV引起的死亡率。相反，暴露于琥珀色（1800 K）ALAN的鸟类的病毒血症和死亡率较低，与对照组相比（即 自然光线条件）。这项研究表明，ALAN影响鸟类的褪黑激素调节，但是这种作用以及ALAN对传染病反应的影响可以通过特殊的照明技术来改善。