Research Fellow of the Japan Society for the Promotion of Science, Kodaira, Japan.
Department of Sleep-Wake Disorders, National Center of Neurology and Psychiatry, National Institute of Mental Health, Kodaira, Japan.
J Physiol Anthropol. 2023 Jun 24;42(1):11. doi: 10.1186/s40101-023-00328-1.
Physiological effects of light exposure in humans are diverse. Among them, the circadian rhythm phase shift effect in order to maintain a 24-h cycle of the biological clock is referred to as non-visual effects of light collectively with melatonin suppression and pupillary light reflex. The non-visual effects of light may differ depending on age, and clarifying age-related differences in the non-visual effects of light is important for providing appropriate light environments for people of different ages. Therefore, in various research fields, including physiological anthropology, many studies on the effects of age on non-visual functions have been carried out in older people, children and adolescents by comparing the effects with young adults. However, whether the non-visual effects of light vary depending on age and, if so, what factors contribute to the differences have remained unclear. In this review, results of past and recent studies on age-related differences in the non-visual effects of light are presented and discussed in order to provide clues for answering the question of whether non-visual effects of light actually vary depending on age. Some studies, especially studies focusing on older people, have shown age-related differences in non-visual functions including differences in melatonin suppression, circadian phase shift and pupillary light reflex, while other studies have shown no differences. Studies showing age-related differences in the non-visual effects of light have suspected senile constriction and crystalline lens opacity as factors contributing to the differences, while studies showing no age-related differences have suspected the presence of a compensatory mechanism. Some studies in children and adolescents have shown that children's non-visual functions may be highly sensitive to light, but the studies comparing with other age groups seem to have been limited. In order to study age-related differences in non-visual effects in detail, comparative studies should be conducted using subjects having a wide range of ages and with as much control as possible for intensity, wavelength component, duration, circadian timing, illumination method of light exposure, and other factors (mydriasis or non-mydriasis, cataracts or not in the older adults, etc.).
人体暴露于光线下的生理效应多种多样。其中，为了维持生物钟 24 小时周期的昼夜节律相位移动效应，被统称为光的非视觉效应，包括褪黑素抑制和瞳孔对光反射。光的非视觉效应可能因年龄而异，明确光的非视觉效应的年龄相关性差异对于为不同年龄段的人提供合适的光照环境非常重要。因此，在包括生理人类学在内的各个研究领域中，许多研究通过比较年轻人与老年人、儿童和青少年的效应，对年龄对非视觉功能的影响进行了研究。然而，光的非视觉效应是否因年龄而异，以及哪些因素导致了差异，这些问题仍不清楚。在本综述中，为了回答光的非视觉效应是否确实因年龄而异这一问题，呈现并讨论了过去和近期有关光的非视觉效应的年龄相关性差异的研究结果。一些研究，尤其是针对老年人的研究，表明了非视觉功能包括褪黑素抑制、昼夜节律相位移动和瞳孔对光反射等方面的年龄相关性差异，而其他研究则没有发现差异。表明光的非视觉效应存在年龄相关性差异的研究怀疑衰老性瞳孔缩小和晶状体混浊是导致差异的因素，而表明不存在年龄相关性差异的研究则怀疑存在代偿机制。一些针对儿童和青少年的研究表明，儿童的非视觉功能可能对光非常敏感，但与其他年龄组进行比较的研究似乎有限。为了详细研究非视觉效应的年龄相关性差异，应使用具有广泛年龄范围的受试者进行比较研究，并尽可能控制光照的强度、波长成分、持续时间、昼夜节律定时、光照方法和其他因素（老年人的散瞳或不散瞳、白内障或无白内障等）。
