Towards an evidence-based integrative lighting score: a proposed multi-level approach

Ann Med. 2024 Dec;56(1):2381220. doi: 10.1080/07853890.2024.2381220. Epub 2024 Jul 25.

Abstract

Background: Human circadian clocks are synchronized daily with the external light-dark cycle and entrained to the 24-hour day. There is increasing evidence that a lack of synchronization and circadian entrainment can lead to adverse health effects. Beyond vision, light plays a critical role in modulating many so-called non-visual functions, including sleep-wake cycles, alertness, mood and endocrine functions. To assess (and potentially optimize) the impact of light on non-visual functions, it is necessary to know the exact 'dose' (i.e. spectral irradiance and exposure duration at eye level) of 24-hour light exposures, but also to include metadata about the lighting environment, individual needs and resources.

Problem statement: To address this problem, a new assessment tool is needed that uses existing metrics to provide metadata and information about light quality and quantity from all sources. In this commentary, we discuss the need to develop an evidence-based integrative lighting score that is tailored to specific audiences and lighting environments. We will summarize the most compelling evidence from the literature and outline a future plan for developing such a lighting score using internationally accepted metrics, stakeholder and user feedback.

Conclusion: We propose a weighting system that combines light qualities with physiological and behavioral effects, and the use of mathematical modelling for an output score. Such a scoring system will facilitate a holistic assessment of a lighting environment, integrating all available light sources.

Keywords: Non-visual effects; alertness; circadian; daylight; health; light quality; lighting score.

Plain language summary

To assess the impact of light on non-visual functions, it is essential to know the exact ‘dose’ of 24-hour light exposures and metadata about the lighting environment and the individual.There is to date no measurement method available that allows a holistic assessment of a lighting environment for visual and non-visual aspects in humans.We discuss the need for an evidence-based integrative lighting score and outline a plan for its development.An evidence-based integrative lighting score, which includes a weighting system to combine light qualities with physiological and behavioral effects, will only be possible by joining forces, knowledge, and methodologies from many disciplines.Such a score entails the potential to sustainably assess, improve and maintain optimized lighting environments that promote the health and productivity of any cohort over the long term.

Publication types

  • Review

MeSH terms

  • Circadian Clocks / physiology
  • Circadian Rhythm* / physiology
  • Circadian Rhythm* / radiation effects
  • Humans
  • Light / adverse effects
  • Lighting* / adverse effects
  • Sleep / physiology
  • Sleep / radiation effects

Grants and funding

This work was partly funded by Innosuisse – Swiss Innovation Agency (Project 63216.1 INNO-ENG). OS received financial support for this work by his employer, Lucerne University of Applied Sciences and Arts, Lucerne, Switzerland, IS was financially supported by the Swiss National Science Foundation (SNSF), and MM by the Velux Foundation, Switzerland.