Red Light & Long-Wavelength Light for Health: What the Science Shows
Summary
Dr. Glen Jeffery, professor of neuroscience at University College London, explains how long-wavelength light (red, near-infrared, and infrared) penetrates the body and improves health by interacting with water surrounding mitochondria, boosting ATP production and reducing cell death. He also warns that modern LED lighting and excessive short-wavelength (blue) light exposure represents a serious and underappreciated public health threat, potentially on par with historical hazards like asbestos.
Key Takeaways
- Long-wavelength light (670–900nm) penetrates the entire body, including through clothing, skin, and even the skull — it scatters internally and affects mitochondria throughout all organs
- 3 minutes of red light (~670nm) in the morning improved color vision by ~20% in nearly all subjects tested, with effects lasting approximately 5 days
- Red light exposure before a meal reduced blood glucose spikes by over 20% in human trials, likely by stimulating mitochondria to consume more glucose
- The morning window (before ~11am) is the optimal time for red light therapy due to circadian shifts in mitochondrial protein activity
- LED and short-wavelength light exposure degrades mitochondrial function in real time — membrane potentials drop and mitochondria become less responsive
- Long-wavelength light works by reducing the viscosity of water surrounding mitochondria, increasing the spin rate of ATP-producing molecular motors
- Red light therapy is most effective as an early intervention — once disease has significantly progressed, benefits are greatly diminished
- All-cause mortality (especially cardiovascular disease and cancer) is lower in people with greater sunlight exposure, according to large studies from Sweden and the University of East Anglia
- Even a small illuminated patch of skin produces systemic mitochondrial effects, suggesting mitochondria across the body act as a coordinated community
- Red light appears to reduce the pace of cell death (apoptosis) by keeping mitochondrial membrane potential above the threshold that triggers the cellular “eat me” signal
Detailed Notes
The Light Spectrum and How It Affects the Body
- Visible light spans roughly 400–700 nanometers (nm)
- Sunlight extends from ~300nm (deep UV) to nearly 3,000nm (deep infrared)
- Short-wavelength light (UV, blue): high-frequency, carries more energy, ionizing at sub-UV wavelengths; blocked by skin and lens; causes sunburn and cataracts with excessive exposure
- Long-wavelength light (red, near-infrared, infrared): low-frequency, non-ionizing, penetrates deeply into tissue
- The body blocks UV at the skin surface, causing inflammation (sunburn) rather than allowing penetration; the lens and cornea also block UV, which is why cataracts can result from chronic overexposure
How Long-Wavelength Light Improves Mitochondrial Function
- Early assumption: mitochondria directly absorb long-wavelength light. This was found to be incorrect
- Revised mechanism: long-wavelength light is absorbed by water surrounding mitochondria (nano-water)
- This absorption reduces water viscosity, increasing the spin rate of the ATP synthase molecular motor
- A secondary downstream effect: more mitochondrial electron transport chain proteins are synthesized, laying more “track” for energy production
- Two effects observed:
- Immediate: faster ATP production
- Longer-term: increased mitochondrial protein synthesis
Light Penetration Through the Body
- Long-wavelength light passes through:
- Skin (only a few percent exits the other side; the rest is absorbed internally)
- Standard clothing — even 6 layers of t-shirt; color of clothing makes no difference
- The skull (confirmed experimentally; bone does not significantly block it)
- The hand (bones are invisible; deoxygenated blood in veins absorbs it, which is what shows up in imaging)
- It does NOT pass through rubber or deoxygenated blood (the latter absorbs it strongly)
- Inside the body, long-wavelength light scatters in all directions, reaching distant tissues
- Application: a biomedical engineer at UCL (Ioannis Tachtsidis) passes red/near-IR light through the skulls of neonates who have had strokes to monitor mitochondrial function as a survival metric — approved through ethics committees
Blood Glucose Regulation
- Bumblebee pilot study: after starvation and glucose loading, bees given red light had significantly lower blood glucose rises than those given blue light
- Human study: subjects fasted overnight, consumed a glucose load, then had red light shined on a small patch of their back (~4×6 inches)
- Result: blood glucose peak reduced by over 20%
- Oxygen consumption simultaneously increased, consistent with mitochondria using more glucose
- The illuminated area was too small to account for the effect locally — confirmed to be a systemic mitochondrial response
- Implication: chronic exposure to blue-shifted LED light throughout the day may be raising blood glucose in a detrimental direction
Vision Improvement with Red Light
- The retina has the highest mitochondrial density of any tissue in the body — it has the highest metabolic rate and ages fastest
- Experiment: subjects tested for color detection thresholds (visual function test using Tritan and Protan axes with added visual noise)
- After a 3-minute exposure to 670nm light, thresholds improved in all but one subject
- Average improvement: ~20%
- Effect lasted 5 days, then reset — same finding replicated in flies, mice, and humans
- The effect is a binary switch, not a dose-response curve — sufficient energy at the right wavelength triggers a lasting 5-day change
- Wavelength guidance:
- 670nm and above works well
- Effects tend to diminish below 650nm
- Near-infrared range (~700–900nm) is also effective
- Energy level: originally tested at 40 mW/cm² (very bright); lab now uses ~8 mW/cm² with equivalent effect; one experiment achieved results near 1 mW/cm² (very dim)
- Eyes open vs. closed: makes little difference — long-wavelength light passes through eyelids effectively
- Age effect: improvements are more pronounced in older individuals (40+) because mitochondria in the aging retina have more room for improvement; younger people can still respond
Circadian Timing of Red Light Therapy
- Morning is the optimal window: from perceived sunrise to approximately 11:00am
- Mitochondrial protein composition changes significantly over a 24-hour cycle
- In the morning, mitochondria are maximally producing ATP; in the afternoon, they are performing other cellular maintenance functions (“doing the ironing”)
- Afternoon red light therapy is significantly less effective
- This pattern is conserved across flies, mice, and humans
Macular Degeneration and Disease Applications
- Initial clinical trial for macular degeneration showed no benefit in the patients themselves — but their husbands (controls without macular degeneration) showed significant vision improvements
- Post-hoc analysis: the patients’ disease had progressed too far for intervention to be effective
- A subsequent study by ophthalmologist Ben Burton (UK), targeting earlier-stage patients, showed significant positive results
- Same limitation found with rheumatoid arthritis trials: subjects with already-deformed joints showed no benefit; intervention needs to occur before structural damage is severe
- Red light reduces the magnitude of apoptosis (cell death) by keeping mitochondrial membrane potential above the threshold that triggers the molecular “eat me” signal
Parkinson’s Disease and Neuroprotection
- Researcher John Mitrofanis (Australia) induced Parkinson’s disease in primates and shined red light on the abdomen — significantly reduced symptoms
- The relevant nucleus (substantia nigra) is deep in the brain; the mechanism is believed to be systemic mitochondrial protection, reducing the pace of dopamine neuron death
- Consistent with the principle that mitochondria across the body communicate and act as a community
The Danger of LED and Short-Wavelength Light
- Modern LEDs are heavily weighted toward short wavelengths (blue-shifted)
- When retinal cells (in mice) are exposed to LED light, mitochondria can be observed in real