Recommendations for daytime, evening, and nighttime indoor light exposure to best support physiology, sleep, and wakefulness in healthy adults

TLDR

Ocular light exposure influences circadian rhythms, sleep, neuroendocrine, and cognitive functions, yet prevailing patterns often fail to optimally engage these effects, prompting new opportunities to adjust lighting for better health and performance. The report aims to provide expert consensus lighting recommendations, expressed as melanopic equivalent daylight illuminance, to optimize health and performance. The recommendations are grounded in a new international standard that quantifies light’s effect on melanopsin‑expressing retinal neurons using melanopic equivalent daylight illuminance. The recommendations are supported by detailed analysis of human circadian, neuroendocrine, and alerting responses to ocular light, offering a straightforward framework for lighting design and practice.

Abstract

Ocular light exposure has important influences on human health and well-being through modulation of circadian rhythms and sleep, as well as neuroendocrine and cognitive functions. Prevailing patterns of light exposure do not optimally engage these actions for many individuals, but advances in our understanding of the underpinning mechanisms and emerging lighting technologies now present opportunities to adjust lighting to promote optimal physical and mental health and performance. A newly developed, international standard provides a SI-compliant way of quantifying the influence of light on the intrinsically photosensitive, melanopsin-expressing, retinal neurons that mediate these effects. The present report provides recommendations for lighting, based on an expert scientific consensus and expressed in an easily measured quantity (melanopic equivalent daylight illuminance (melaponic EDI)) defined within this standard. The recommendations are supported by detailed analysis of the sensitivity of human circadian, neuroendocrine, and alerting responses to ocular light and provide a straightforward framework to inform lighting design and practice.