This study investigated how light exposure duration affects melatonin suppression, a well-established marker of circadian phase, and whether adolescents (13–18 years) are more sensitive to short-wavelength (blue) light than adults (32–51 years). Twenty-four participants (12 adolescents, 12 adults) were exposed to three lighting conditions during successive 4-h study nights that were separated by at least one week. In addition to a dim light (<5 lux) control, participants were exposed to two light spectra (warm (2700 K) and cool (5600 K)) delivering a circadian stimulus of 0.25 at eye level. Repeated measures analysis of variance revealed a significant main effect of exposure duration, indicating that a longer duration exposure suppressed melatonin to a greater degree. The analysis further revealed a significant main effect of spectrum and a significant interaction between spectrum and participant age. For the adolescents, but not the adults, melatonin suppression was significantly greater after exposure to the 5600 K intervention (43%) compared to the 2700 K intervention (29%), suggesting an increased sensitivity to short-wavelength radiation. These results will be used to extend the model of human circadian phototransduction to incorporate factors such as exposure duration and participant age to better predict effective circadian stimulus.

中文翻译：

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暴露时间和光谱对青少年和成人夜间褪黑激素抑制的影响

这项研究调查了光照持续时间如何影响褪黑激素抑制，这是一种公认​​的昼夜节律标志，以及青少年（13-18 岁）是否比成年人（32-51 岁）对短波（蓝色）光更敏感。24 名参与者（12 名青少年，12 名成人）在连续 4 小时的研究之夜暴露在三种光照条件下，这些夜晚至少相隔一周。除了昏暗的灯光 (<5 lux) 控制之外，参与者还暴露于两种光谱（暖 (2700 K) 和冷 (5600 K)），在眼睛水平提供 0.25 的昼夜节律刺激。重复测量方差分析揭示了暴露时间的显着主效应，表明暴露时间越长，褪黑激素的抑制程度越大。分析进一步揭示了频谱的显着主效应以及频谱与参与者年龄之间的显着相互作用。对于青少年，但不是成年人，与 2700 K 干预 (29%) 相比，5600 K 干预 (43%) 暴露后褪黑激素抑制显着更大，表明对短波辐射的敏感性增加。这些结果将用于扩展人类昼夜节律光转导模型，以纳入暴露持续时间和参与者年龄等因素，以更好地预测有效的昼夜节律刺激。表明对短波辐射的敏感性增加。这些结果将用于扩展人类昼夜节律光转导模型，以纳入暴露持续时间和参与者年龄等因素，以更好地预测有效的昼夜节律刺激。表明对短波辐射的敏感性增加。这些结果将用于扩展人类昼夜节律光转导模型，以纳入暴露持续时间和参与者年龄等因素，以更好地预测有效的昼夜节律刺激。