Blue Light and Melatonin: What the Research Actually Says

Blue light has become the villain of the sleep world, with countless products promising to block it and restore your natural sleep. But what does the science actually say?

Understanding Blue Light

Blue light is part of the visible light spectrum, with wavelengths between 380-500 nanometers. It's abundant in sunlight and is what makes the sky appear blue. Our screens emit blue light, but so do LED bulbs and fluorescent lights.

The Melatonin Connection

Your brain's pineal gland produces melatonin in response to darkness. Research has shown that light exposure, particularly blue light, can suppress melatonin production. The photoreceptors responsible for this (intrinsically photosensitive retinal ganglion cells, or ipRGCs) are most sensitive to blue light around 480nm.

What the Studies Show

Evidence For Blue Light Effects

• A Harvard study found blue light suppressed melatonin twice as long as green light
• Research in teenagers showed screen use before bed delayed melatonin onset by 30 minutes
• Night shift workers exposed to blue light had significantly disrupted circadian rhythms

Important Context

• Intensity matters more than color: The brightness of the light is often more impactful than its spectrum
• Duration matters: Brief exposure has minimal effects; prolonged exposure is more problematic
• Distance matters: Holding a phone close to your eyes delivers more light than a distant TV
• Individual variation: Some people are more sensitive to light's effects than others

Practical Recommendations

What Works

• 1. Dim all lights 2 hours before bed—this is more effective than just blocking blue light
• 2. Use night mode on devices—reduces brightness and shifts colors warmer
• 3. Stop screen use 1 hour before bed if you're sensitive
• 4. Get bright light exposure during the day—this strengthens your circadian rhythm

What's Overhyped

• Blue light glasses during the day: Daytime blue light exposure is beneficial and helps regulate your circadian rhythm
• Extreme blue light blocking: Some amber glasses block so much light they can affect evening activities

The Bottom Line

Blue light does affect melatonin, but it's one piece of a larger puzzle. Focus on overall light hygiene: bright days, dim evenings, and consistent sleep timing. Blue light blocking can help, but it's not a magic solution for poor sleep habits.