Research

Hormonal

Chronic exposure to blue light at night, particularly from artificial sources like LED screens, disrupts circadian rhythms by suppressing melatonin, leading to sleep onset delays and increased health risks such as breast cancer in shift workers.

If you must use screens at night, use software that removes blue wavelengths (night shift mode) or wear amber-tinted glasses. Prioritize bright morning sunlight to help reset your clock after a night of disrupted light. For shift workers, strategic light exposure (bright light during shift, dark glasses on commute home) is critical.

GoodSupportsHIGH confidence
Chronic exposure to low-intensity blue light directly before bedtime, may have serious implications on sleep quality, circadian phase and cycle durations. ... Prolonged periods of work during the night are the most extreme source of wrong timed exposure to light, which leads to a simultaneous reduction of melatonin production, sleep deprivation and circadian disruption.
Siegfried Wahl et al. · Journal of Biophotonics · 2019

Why this rating

Supported by epidemiological studies and meta-analyses linking shift work (nighttime light exposure) to increased breast cancer risk.

Source

The inner clock—Blue light sets the human rhythm

Siegfried Wahl et al. · Journal of Biophotonics · 2019

DOI 10.1002/jbio.201900102

narrative_reviewCited 272×
Read the paper
DOI resolved against Crossref · corpus check 2026-06-10

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