The Dark Side of LED Lights
- Oct 13
- 2 min read
By Ken Ceder
Executive Director Science of Light
As Executive Director of the nonprofit research organization Science of Light, I want to raise awareness about a critical, yet often overlooked issue in modern lighting. While solid-state LED (light-emitting diode) technology delivers impressive energy savings and longevity, its vital biological effects are rarely considered by lighting engineers and regulators.
The current emphasis on visible brightness and efficiency has excluded important non-visible wavelengths—especially near-infrared (NIR)—that are essential for human health, particularly for eye function and cellular vitality.
Physicists and manufacturers tend to dismiss infrared radiation as mere thermal waste. Yet decades of medical research show otherwise. Hundreds of peer-reviewed studies demonstrate that NIR wavelengths improve tissue repair, regeneration, circulation, and cellular energy production. While invisible and not perceived as heat, NIR helps prime retinal cells for repair, reduces the risk of macular degeneration, and supports ATP synthesis—the foundation of cellular energy. By contrast, blue light—the dominant emission in most LEDs—offers no such reparative effect.
The lack of red and NIR frequencies in standard indoor LEDs creates a spectral imbalance. Excessive blue light exposure generates reactive oxygen species (ROS) which, without the counterbalancing support of red and NIR wavelengths, leads to cell damage, tissue stress, and accelerated aging. Studies link blue-enriched LEDs to increased risks of eye strain, macular degeneration, disrupted circadian rhythms, and cellular dysfunction beyond the retina itself.
Natural sunlight, much like the old incandescent bulb, always contains ample red and near-infrared light alongside blue, offering a spectrum shaped by evolution to stimulate and repair simultaneously. In contrast, most indoor LED environments overexpose people to short-wavelength blue light while suppressing the regenerative power of longer wavelengths—a combination unprecedented in nature with measurable consequences for retinal health, sleep quality, mitochondrial efficiency, and hormone regulation.
As photobiology expert Dr. Alexander Wunsch states:
“LED light exposure that is not balanced with full spectrum sunlight, loaded with the red parts of the spectrum, is always damaging to your biology.”
This underscores an urgent reality: energy efficiency alone is not enough. Lighting must also be evaluated for spectral completeness and its compatibility with biological repair processes.
In conclusion:
Neglecting red and near-infrared light in our built environments risks long-term biological harm, especially as people spend most of their waking hours indoors. To be truly health-supportive, lighting must integrate the spectrum’s regenerative components, mirroring the balanced qualities of natural sunlight—not just its brightness.
Science of Light is pleased to share additional ‘light & health’ research and information at both of our websites: scienceoflight.org and solshine.org.
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