Summary
Artificial light at night suppresses melatonin at extremely low intensities across vertebrates, with thresholds as low as 0.01–0.03 lx in fish and rodents and approximately 6 lx in sensitive humans, underscoring the need for strict nighttime lighting controls. Lighting designers and healthcare planners should treat even dim nighttime illumination as potentially disruptive to circadian health, particularly in environments where sleep quality matters.
Key Findings
- Melatonin suppression thresholds range from 0.01–0.03 lx in fishes and rodents to ~6 lx in sensitive humans under ALAN exposure.
- In many studies, melatonin suppression was observed at the minimum light levels tested, suggesting true thresholds may be even lower than currently documented.
- Melatonin suppression is wavelength-dependent, with shorter (blue) wavelengths being more potent suppressors, relevant to the widespread transition to LED lighting.
- No studies were identified for amphibians and reptiles, and long-term impacts of low-level ALAN exposure remain unknown across most vertebrate groups.
- The systematic review found a consistent pattern across vertebrate taxa: circadian disruption via melatonin suppression is a widespread and sensitive response to artificial light at night.
Categories
Sleep & Circadian Health: Reviews how artificial light at night suppresses melatonin and disrupts circadian rhythms across vertebrates including humans.
The Science of Light: Discusses photoreceptor systems, spectral sensitivity, and threshold light intensities for melatonin suppression across vertebrate taxa.
Author(s)
M Grubisic, A Haim, P Bhusal, DM Dominoni
Publication Year
2019
Number of Citations
154
Related Publications
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The Science of Light
- Phototransduction by retinal ganglion cells that set the circadian clock
- Color appearance models
- The mammalian circadian timing system: organization and coordination of central and peripheral clocks
- Diminished pupillary light reflex at high irradiances in melanopsin-knockout mice
- Melanopsin is required for non-image-forming photic responses in blind mice