Non-image-forming effects of daytime electric light exposure in humans: A systematic review and meta-analyses of physiological, cognitive, and subjective outcomes

Lasauskaite, R, Wüst, L, Schöllhorn, I, Richter, M and Cajochen, C (2025) Non-image-forming effects of daytime electric light exposure in humans: A systematic review and meta-analyses of physiological, cognitive, and subjective outcomes. LEUKOS: The Journal of the Illuminating Engineering Society. ISSN 1550-2724

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Abstract

Light exerts numerous non-visual or non-image forming, effects—such as its impact on melatonin suppression, circadian phase-shifts, sleep quality, and alertness. While research typically focuses on evening and nighttime effects, a growing number of studies described light’s non-visual impact during daytime (from 7 am to 7 pm). In this work, we systematically analysed 141 peer-reviewed articles (150 studies) published by March 2023, encompassing 5401 healthy volunteers mainly aged 18-30. We calculated effect sizes using data extracted from the text, tables, or graphs and conducted 43 individual multilevel meta-analyses of physiological, cognitive, and subjective outcomes, divided into effects of light intensity and light spectral properties. We retained 17 meta-analyses that were based on data from more than 10 studies. Our results showed that higher light intensity enhances EEG brain wave-activity associated with heightened cognitive processing and attention, leads to faster response times, and reduces subjective sleepiness. The effect sizes were small. Meta-analyses of the effects of spectral characteristics of light did not show any significant summary effects. Overall, our findings suggest that higher ambient light intensities during daytime may be beneficial, but benefits are likely to be modest in healthy young human adults, who already performing at near-optimal levels.

Item Type:	Article
Uncontrolled Keywords:	0915 Interdisciplinary Engineering; Building & Construction; 4010 Engineering practice and education
Subjects:	B Philosophy. Psychology. Religion > BF Psychology
Divisions:	Psychology (from Sep 2019)
Publisher:	Taylor and Francis Group
Date of acceptance:	4 April 2025
Date of first compliant Open Access:	27 May 2025
Date Deposited:	27 May 2025 09:56
Last Modified:	27 May 2025 10:15
DOI or ID number:	10.1080/15502724.2025.2493669
URI:	https://researchonline.ljmu.ac.uk/id/eprint/26417

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