Research studies on LED light exposure and cortisol are inconsistent and not comparable due to different types of light, exposure times, and sample sizes. Therefore, one hour of standardized exposure LED light at different intensities and the spectral composition during the post-awakening phase at 7:30 were compared. A sample of 23 (Study 1) and 26 (Study 2) healthy males were randomly assigned to: 1) bright white light (414 lux) and 2) dim darkened light (<2 lux) as well as 3) red light (235 lux) and 4) blue light (201 lux) exposure conditions. Results from repeated measures ANOVA confirm that light exposure affects the cortisol concentration. Study 1 revealed an increase in the saliva cortisol concentration after bright light exposure compared to dim light. An increase in the cortisol concentration of blue light compared to red light (Study 2) and dim light was found. This study shows that bright light and blue light affect the cortisol response in contrast to dim light and red light conditions. The HPA axis showed a stimulatory effect by bright versus dim light and different wavelengths of light exposure.

• Lay summary

• The effects of LED light exposure on the stress hormone cortisol were investigated. The light exposure took place during the hours people would start working at the office. The results showed that after one hour of exposure to bright light or blue light the stress hormones increase in contrast to dim light and red light conditions. Thus, stress hormones can be altered by the types of light people are exposed to.

由于不同类型的光，曝光时间和样品量，有关LED曝光和皮质醇的研究不一致，且不可比。因此，比较了在7:30的唤醒后阶段在不同强度下的一小时标准化曝光LED光和光谱组成。将23位（研究1）和26位（研究2）健康男性的样本随机分配给：1）亮白光（414 lux）和2）暗光（<2 lux）以及3）红光（235 lux）和4）蓝光（201 lux）曝光条件。重复测量方差分析的结果证实曝光会影响皮质醇浓度。研究1表明，与暗光相比，强光照射后唾液皮质醇浓度增加。发现与红光（研究2）和暗光相比，蓝光的皮质醇浓度增加。这项研究表明，与暗光和红光条件相比，亮光和蓝光会影响皮质醇的响应。HPA轴通过亮光与暗光以及不同波长的曝光显示出刺激作用。

• 放置摘要

• 研究了LED曝光对应激激素皮质醇的影响。曝光发生在人们开始在办公室工作的时间。结果表明，与暗光和红光条件相比，暴露于强光或蓝光一小时后，应激激素增加。因此，压力激素可能会因人们所接触的光的类型而改变。