LIGHTING FOR HEALTHY LONGEVITY AT HOME: A NARRATIVE REVIEW

Modern humans spend most of their lives indoors; as a result, the domestic light environment has become a pervasive determinant of physiology and well-being. Light entrains circadian rhythms via intrinsically photosensitive retinal ganglion cells (ipRGCs), modulates endocrine activity such as melatonin and cortisol secretion, and influences sleep timing, mood regulation, and metabolic homeostasis. These processes are closely connected with healthy ageing and disease prevention. This review synthesises experimental, clinical, and epidemiological evidence on how natural and artificial light’s spectral quality, intensity, timing, and duration in residential settings affect circadian alignment, sleep architecture, cardiometabolic function, ocular health, and skin protection. We examine mechanistic pathways linking light exposure to neuroendocrine and metabolic outcomes, highlight findings from randomised controlled trials and large-scale observational studies, and evaluate consensus recommendations from international health and lighting organisations. Practical strategies for optimising lighting design in bedrooms, living areas, and home workspaces are presented, including approaches tailored for vulnerable groups such as older adults, shift workers, and individuals with circadian rhythm disorders. Finally, we identify key knowledge gaps, limitations of current research, and priorities for future interdisciplinary studies aimed at translating chronobiology into evidence-based architectural and public health interventions.