In the field of physiological anthropology, studies on the non-visual effects of light have been conducted since the early 1990s. Although intrinsically photosensitive retinal ganglion cells (ipRGCs) are thought to be primarily involved in non-visual functions, recent studies in animals and healthy humans have revealed that cones may also contribute to non-visual functions such as circadian entrainment, suppression of melatonin secretion, and pupillary light reflex. In this paper, we reviewed recent studies on the role of cones in these non-visual functions.

In this study, the effects of black tea aroma on sleep and psychological and cognitive functions were investigated in community-dwelling elderly women. Nocturnal inhalation of black tea aroma significantly shortened sleep latency and bed out latency while significantly increasing sleep efficiency. In the evaluation of psychological function using the MOS 36-Item Short Form Health Survey subscale, physical functioning and vitality significantly improved, and the evaluation of cognitive function showed a significant decrease in short-term memory reaction times. Significant correlations were found between shortened sleep latency and shorter short-term memory reactions, shortened sleep latency and higher Mini-Mental State Examination scores, shortened bed out latency and lower Athens Insomnia Scale scores, and shortened bed out latency and lower Self-rating Depression Scale scores. These results suggest that improved sleep onset and awakening resulting from nighttime exposure to black tea aroma may improve cognitive function and reduce the feeling of insomnia and depression.