Blue light (evening artificial light at night)
Toxins · Circadian disruptor
Moderate priority
What this is
Evening light > blue light specifically — all bright evening light suppresses melatonin; blue-blockers partially mitigate screens. Chang 2015 PNAS: evening reading on iPad delayed melatonin 1.5 hr vs print book. Morning bright light is the other half of the equation for circadian robustness. 'Blue light damage to eyes from screens' claims are overblown — consumer devices are far below damaging thresholds.
Mechanism
Short-wavelength visible light (460-480 nm peak) strongly suppresses melatonin via ipRGC-melanopsin signaling; evening exposure shifts circadian phase, delays sleep onset, and may contribute to metabolic and mental health consequences of shift work
Dose & route
Dim/warm evening light; f.lux / Night Shift; blue-blocking glasses 2-3 hours before bed (if heavy evening screen use); morning bright light
Citations
- https://pubmed.ncbi.nlm.nih.gov/25535358/
- https://pubmed.ncbi.nlm.nih.gov/31390415/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC6091336/
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This is an independent synthesis of published research by a non-clinician. Scores are opinions supported by citations, not prescriptions. See the full disclaimer and methodology for how this score was produced and what it does and doesn't mean.