Mekschrat Liza, Straßer Torsten, Ghassabei Shiwa, Schmalbach Bjarne, Niedling Mathias, Petrowski Katja
Medical Psychology and Medical Sociology, Johannes Gutenberg University Mainz, Mainz, Germany.
Institute for Ophthalmic Research, Center for Ophthalmic Research, Eberhart Karls University Tuebingen, Tuebingen, Germany.
Neuropsychobiology. 2024;83(5-6):183-192. doi: 10.1159/000541230. Epub 2024 Oct 11.
Light is a key factor in moderating human alertness, both subjective and objective. However, the methodology applies in research on the effects of exposure to light of different wavelengths and intensities on objective and subjective alertness varies greatly and evidence on objective alertness in particular is still inconclusive. Thus, the present, highly standardized within-subject laboratory study on N = 44 healthy males explored how LED light of different intensities (dim vs. bright light) and wavelengths (red vs. blue) affected objective (reaction time/RT) as well as subjective (sleepiness) alertness in the morning after wake-up.
Participants spent two separate nights in the laboratory and were exposed to either one of the two light intensities or colors for 60 min after wake-up. Additionally, they indicated their sleepiness on the Karolinska Sleepiness Scale and participated in an auditory RT task before and after light intervention. It was hypothesized that both bright and blue light would lead to greater subjective and objective alertness when compared to dim and red light, respectively.
Results indicated that average RTs were longer for participants in the bright light condition (p = 0.004, f2 = 0.07) and that RTs decreased post-light exposure irrespective of light being dim or bright (p = 0.026, f2 = 0.07). However, dim versus bright light and RT did not interact (p = 0.758, f2 = 0.07). Chronotype was a significant covariate in the interaction of dim versus bright light and subjective sleepiness (p = 0.008, f2 = 0.22). There was no difference in RTs when comparing exposure to red or blue light (p = 0.488, f2 = 0.01). Findings on subjective sleepiness and light of different wavelengths revealed that sleepiness was reduced after light exposure (p = 0.007, f2 = 0.06), although the wavelength of light did not appear to play a role in this effect (p = 0.817, f2 = 0.06).
Hence, neither of the hypotheses could be confirmed. However, they indicated that evening types might benefit from exposure to bright light regarding sleepiness, but not morning types.
光无论是在主观还是客观上，都是调节人类警觉性的关键因素。然而，研究不同波长和强度的光照对客观和主观警觉性影响的方法差异很大，尤其是关于客观警觉性的证据仍然没有定论。因此，本研究对44名健康男性进行了高度标准化的受试者内实验室研究，探讨了不同强度（暗光与亮光）和波长（红光与蓝光）的LED光如何影响醒来后早晨的客观（反应时间/RT）以及主观（困倦）警觉性。
参与者在实验室度过两个独立的夜晚，醒来后接受两种光强度或颜色中的一种照射60分钟。此外，他们在卡罗林斯卡困倦量表上表明自己的困倦程度，并在光照干预前后参与听觉反应时间任务。假设与暗光和红光相比，亮光和蓝光分别会导致更高的主观和客观警觉性。
结果表明，亮光条件下参与者的平均反应时间更长（p = 0.004，f2 = 0.07），并且无论光照是暗还是亮，光照后反应时间都会缩短（p = 0.026，f2 = 0.07）。然而，暗光与亮光和反应时间之间没有相互作用（p = 0.758，f2 = 0.07）。在暗光与亮光和主观困倦的相互作用中，生物钟类型是一个显著的协变量（p = 0.008，f2 = 0.22）。比较红光或蓝光照射时，反应时间没有差异（p = 0.488，f2 = 0.01）。关于主观困倦和不同波长光的研究结果表明，光照后困倦程度降低（p = 0.007，f2 = 0.06），尽管光的波长在这种影响中似乎没有起到作用（p = 0.817，f2 = 0.06）。
因此，两个假设均未得到证实。然而，研究表明，夜型人在困倦方面可能会从亮光照射中受益，但晨型人则不然。
