The relationship between blue light and melatonin suppression is one of the most well-established findings in circadian biology research.
Harvard Health research confirmed that blue light suppresses melatonin for approximately twice as long as green light and shifts circadian rhythms significantly.
A 2025 MDPI study compared red and blue light directly and found that after two hours blue light maintained melatonin suppression at 7.5 pg/mL while red light allowed recovery to 26.0 pg/mL.
A systematic review published in Chronobiology International 2018 confirmed across multiple peer-reviewed studies that evening blue light exposure suppresses melatonin and disrupts REM sleep parameters.
The evidence is not anecdotal. It is consistent across decades of independent research.
Here are the studies:
Journal of Athletic Training 2012 — Effect of Low-Level Laser Therapy on Serum Melatonin and Sleep Quality.
MDPI Life Journal 2025 — Comparative Effects of Red and Blue LED Light on Melatonin Levels During Three-Hour Exposure in Healthy Adults.
Harvard Health Updated 2024 — Blue Light Has a Dark Side.
Chronobiology International 2018 — Systematic Review of Light Exposure Impact on Human Circadian Rhythm.