Assessing the Effects of Polychromatic Light Exposure on Mood in Adults: A Systematic Review Contrasting α-opic Equivalent Daylight Illuminances

ABSTRACT

This is a systematic review of studies assessing the effects of polychromatic (white) ambient light on mood in healthy adults. We hypothesized that higher melanopic equivalent daylight illuminances (EDI) would be associated with better mood. The search identified 2,994 publications, of which 14 met inclusion criteria. The resulting database included the spectral power distributions, illuminances, mood measures, and methods. We used the CIE S026 toolbox to calculate the five α-opic EDI values to characterize the light exposures in each study. Regression models tested the associations between predictors α-opic EDI, duration, and timing, and the outcome, mood. The results showed that none of the five α-opic values were significantly associated with mood (all estimates <0.044, p > .490). A longer duration of light exposure (all estimates <0.154, p < .018) and timing of light exposure in the morning (all estimates <0.233, p < .001) were associated with better mood, but these effects did not persist after adjusting for the data being nested within studies. Average mood scores remained reasonably consistent across different α-opic EDI profiles, suggesting that exposure profiles might not influence mood. Notably, none of the studies included had an experimental condition with a peak for melanopic EDI greater than the other α-opic EDI values, therefore the hypothesized association between melanopic EDI and mood could not be tested. Future research designs should contrast selected light parameters to identify the photoreceptors involved in the processes of interest.

KEYWORDS:

• Polychromatic light
• mood
• light exposure
• ipRGC
• α-opic equivalent daylight illuminance

Acknowledgments

The project has been overseen by a Scientific Advisory Board, the members of which are: Prof. Marc Hébert (U. Laval); Dr. John Hanifin (Thomas Jefferson U.); Dr. John O’Hagan (Public Health England); Dr. Sami Qutob (Health Canada); Dr. Luc Schlangen (Eindhoven University of Technology). We also thank Dr. Luke Price (Public Health England) for assistance with the CIE S026 toolbox and study authors who have shared with us unpublished details about their studies to permit the meta-analysis. At the University of Ottawa, we acknowledge the contributions of J. Despot, A. Haddad, and C. Richards.

Disclosure statement

Jennifer Veitch serves on committees and boards of the IES, the International Commission on Illumination, and the International Organization for Standardization, which write recommendations, standards, and guidance related to the topic of this work. The other authors report no competing interests to declare.

Data availability statement

Requests to access our database of calculated α-opic EDI values and published outcomes can be sent to the corresponding author.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15502724.2023.2219017

Additional information

Funding

This work was supported by a contract from Axis Lighting Inc. to the National Research Council of Canada. Axis Lighting has not been involved in the research planning, data extraction, data analysis, or interpretation of the results.