Light as a modulator of non-image-forming brain functions-positive and negative impacts of increasing light availability
Open accessAbstract
Light use is rising steeply, mainly because of the advent of light-emitting diode (LED) devices. LEDs are frequently blue-enriched light sources and may have different impacts on the non-image forming (NIF) system, which is maximally sensitive to blue-wavelength light. Most importantly, the timing of LED device use is widespread, leading to novel light exposure patterns on the NIF system. The goal of this narrative review is to discuss the multiple aspects that we think should be accounted for when attempting to predict how this situation will affect the NIF impact of light on brain functions. We first cover both the image-forming and NIF pathways of the brain. We then detail our current understanding of the impact of light on human cognition, sleep, alertness, and mood. Finally, we discuss questions concerning the adoption of LED lighting and screens, which offer new opportunities to improve well-being, but also raise concerns about increasing light exposure, which may be detrimental to health, particularly in the evening.
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Light has acute effects on non-image-forming functions, such as circadian rhythms, sleep, mood, and cognitive processes.
“Light has acute effects on non‐image‐forming functions, such as circadian rhythms, sleep, mood, and cognitive processes [61].”
From Ocular light exposure interventions for sleep, circadian rhythms, rest-activity cycles, mood, and cognitive function in older adults: An Overview of Cochrane and non-Cochrane Systematic Reviews (2025) · cites this paper as [61]
The Introduction identifies acute effects of light on alertness and cognitive performance, and Section 5 explicitly describes acute effects on sleep and cognition. But the Introduction places circadian entrainment and mood on a longer timescale, so the source does not support describing all four listed functions as acute effects. (LLM, conf=0.88)
Experimental — accuracy not yet measuredIntrinsically photosensitive retinal ganglion cells contain the light-sensitive pigment melanopsin and play a crucial role in regulating circadian, neuroendocrine, and neurobehavioural functions.
“These cells, which contain the light‐sensitive pigment melanopsin, play a crucial role in regulating circadian, neuroendocrine, and neurobehavioural functions [61].”
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References 208 · Cited by 43
- Authors
- Campbell, I., Sharifpour, R., & Vandewalle, G.
- Affiliations
- University of Liège (BE)
- Corresponding author
- Vandewalle, Gilles
- Venue
- Clocks & Sleep
- Publisher
- MDPI AG
- Published
- 2023-03-17
- Volume
- 5
- Issue
- 1
- Pages
- 116-140
- ISSN
- 2624-5175 (ISSN-L)
- PMC
- PMC10047820
- OpenAlex
- W4327742982
- Cited by
- 43
- References
- 208
- Citations by year
- 2026: 6 · 2025: 15 · 2024: 17 · 2023: 5
- FWCI
- 1.63
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- Locations
- Clocks & Sleep (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- ORBi (University of Liège) (submittedVersion, other-oa)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Funders
- Fonds National de la Recherche Scientifique (FRS-FNRS; Research credit–CDR and FRIA bursary) (860613)
- European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie (860613)
- ULiège-Valeo Innovation Chair “Health and Well-Being in Transport” (860613)
- Sanfran (LIGHT-CABIN project), ULiège and Leon Fredricq Foundation (860613)
- Topics
- Life Sciences › Neuroscience › Endocrine and Autonomic Systems › Circadian rhythm and melatonin
- Physical Sciences › Environmental Science › Global and Planetary Change › Impact of Light on Environment and Health
- Life Sciences › Agricultural and Biological Sciences › Plant Science › Light effects on plants
- Keywords
- non-image-forming vision, blue light, light-emitting diodes, light exposure, circadian rhythm, sleep, alertness, mood, cognition, screen time, evening light exposure
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