Fundamental Spectral Boundaries of Circadian Tunability

Jeroen Cerpentier,Youri Meuret

doi:10.1109/jphot.2021.3098903

Abstract

The discovery of melanopsin and the non-visual impact of light, lead to a new era in lighting design. Using a melanopic action spectrum, the CIE introduced the melanopic efficacy of luminous radiation (MELR), which quantifies the influence of light on melanopsin. A significant amount of research has been conducted on the possible variation of this MELR and other related metrics for various practical lighting settings, but the fundamental spectral boundaries have not yet been disclosed. Without these limits, it is difficult to assess if a certain lighting system really achieves high or low MELR. This paper determines these fundamental MELR boundaries for different CCT and certain minimal TM-30 R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> values, using a a flexible parametrization of the light source spectrum that is optimized with Differential Evolution. The obtained results show that with increasing CCT, the interval between the theoretical MELR extrema increases slightly, while the opposite occurs when increasing the minimal TM-30 R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> value. The same parametric model and optimization approach is also used to determine the maximal Luminous Efficacy of Radiation (LER) within the obtained MELR limits.

Highlights

I N this day and age, people spend most of their time indoors, exposed to artificial light [1], [2]
When light falls on the eye, the suprachiasmatic nucleus (SCN) receives environmental information from the retina through non-image forming, intrinsically photosensitive retinal ganglion cells, which function as circadian photoreceptors [6], [7]
The sensitivity of the intrinsically photosensitive retinal ganglion cells (ipRGCs) to incoming light is known to be wavelength-dependent, and for lighting applications, this is described by a melanopic action spectrum C(λ), which peaks at λmax = 490 nm

Summary

Introduction

I N this day and age, people spend most of their time indoors, exposed to artificial light [1], [2]. This may disturb the human biological rhythm, and could potentially lead to severe health conditions, such as breast cancer and circadian phase abruption [3], [4]. The ipRGCs express the photopigment melanopsin, which reacts with the incoming light and predominantly influences the excretion of melatonin, a hormone that plays a significant role in sleep cycle moderation [8], [9].

Objectives

Methods

Results

Conclusion