1. Natural Twilight: A Balanced Signal

Full Spectrum, Not Just Blue-Free: Natural twilight is not devoid of blue light. Due to atmospheric scattering, twilight contains a dominant blue peak (~480 nm) balanced with near-infrared (NIR/IR) wavelengths. This full-spectrum balance serves as a natural circadian cue for transitioning from wakefulness to rest.

Implication: The problem isn’t blue light itself but the imbalance in artificial lighting, which lacks NIR/IR wavelengths. Excess narrowband blue disrupts our biology.

2. Red/NIR Light and Its Role in Circadian Health

Broadband, Thermal Light is Beneficial: Incandescent bulbs, fire, and candles emit a broad-spectrum, thermal light, including red/NIR wavelengths, mimicking twilight and supporting circadian rhythms.

Red Light Therapy Nuance: Red and NIR light benefit mitochondrial function and counteract negative effects of isolated blue light. The key isn’t blocking blue but restoring missing complementary spectra.

3. The Critique of Blue Blockers & Monochromatic Solutions

Risk of “Melanopsin Tunnel Vision”: Over-reliance on blue light blockers filters out beneficial NIR/IR wavelengths, leading to an unnatural monochromatic stimulus.

Unintended Consequences: Photoreceptors exist beyond the eyes, including in the skin, making it crucial to address overall light balance rather than solely blocking blue.

4. The Role of “Lu” (Light Intensity & Spectrum Balance)

Beyond Wavelengths – Intensity Matters: Light intensity (lux) affects circadian biology. Natural light provides balanced doses of blue and red/NIR, a balance lacking in artificial sources.

Designing Better Lighting: Instead of relying on blue blockers, an ideal approach is designing dynamic lighting that mimics natural full-spectrum sunlight.

Key Steps for a Circadian Lighting Strategy

Morning Activation

• Expose yourself to bright, full-spectrum light upon waking.
• Prefer natural sunlight or artificial light that mimics full-spectrum daylight.

Midday Optimization

• Maintain high-intensity, balanced-spectrum lighting for alertness.

Evening Transition

• Gradually reduce light intensity and shift to warmer tones.
• Use lighting that mimics twilight (blue light balanced with red/NIR).

Nighttime Environment

• Opt for broad-spectrum thermal lighting instead of LED.
• Minimize reliance on blue blockers; use lights that naturally mimic twilight.

Dynamic, Automated Controls

• Use smart lighting systems that adjust brightness and spectrum throughout the day.

Context & Intensity Considerations

• Ensure light exposure aligns with time of day and natural intensity levels.

Monitor & Adjust

• Track how lighting impacts sleep and energy levels.
• Fine-tune lighting strategy based on personal response.

Thank you for reading! To your best health!