Huberman Lab

Using Red Light to Improve Metabolism & the Harmful Effects of LEDs | Dr. Glen Jeffery

December 1, 2025

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  • Short-wavelength light, particularly from LEDs, is a significant public health concern due to its detrimental effects on mitochondrial health, while long-wavelength light (red/infrared) can enhance mitochondrial function. 
  • Long-wavelength light penetrates deeply through the skin, clothing, and even the skull, leading to systemic effects such as improved blood glucose regulation when applied to a small area of the body. 
  • A brief, single exposure to long-wavelength light (around 670 nm) directed toward the eyes can improve color vision thresholds by approximately 20%, with the effect reliably lasting for five days, indicating a fundamental biological switch. 
  • The timing of light exposure is critical, with morning light exposure yielding the biggest positive effects on mitochondrial function compared to the afternoon. 
  • Artificial LED lighting, due to its short-wavelength enrichment and lack of balanced spectrum, is a significant concern potentially causing mitochondrial dysfunction, weight gain, and metabolic imbalance in animal models. 
  • Early intervention with long-wavelength light therapy is crucial for conditions like macular degeneration and rheumatoid arthritis, as the benefits diminish significantly once the disease has progressed substantially. 
  • Dr. Jeffery's research showed positive, life-changing improvements in children with mitochondrial disease using light-based interventions, leading to plans for further clinical trials, including one for retinitis pigmentosa. 
  • Dr. Jeffery is actively promoting the use of long-wavelength light (like changing light bulbs) as a low-cost intervention for mitochondrial health, despite concerns about new hospital designs using poor-quality LEDs that block infrared light. 
  • Andrew Huberman expressed deep appreciation for Dr. Jeffery's shift in research focus toward public health applications of light, his willingness to provide actionable advice, and his meticulous scientific work. 

Segments

LED Light Danger and Mitochondria
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(00:00:00)
  • Key Takeaway: LED light exposure causes mitochondrial function to decline, evidenced by reduced responsiveness and membrane potentials.
  • Summary: Exposure to light found in LEDs is highly concerning, potentially on the level of asbestos as a public health issue. In mice, LED light exposure causes mitochondria to decline in function, showing reduced responsiveness and lower membrane potentials. This immediate observation highlights the negative impact of short-wavelength light on cellular energy production.
Light Spectrum Framework
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(00:03:48)
  • Key Takeaway: Visible light spans 400 to 700 nanometers, but sunlight extends far beyond this into the infrared (up to 3,000 nm) and deep blue/UV (down to 300 nm).
  • Summary: Light is a continuum of wavelengths, with the visible range being only a small portion of what the sun emits. Short-wavelength light (like UV) carries a high ‘kick’ and causes damage like sunburn, while long wavelengths carry different energy and penetrate deeper.
Short Wavelength Radiation Effects
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(00:06:30)
  • Key Takeaway: Short wavelengths below UV are ionizing radiation capable of altering DNA, whereas longer wavelengths are non-ionizing.
  • Summary: Short wavelengths carry enough energy to be ionizing radiation, which can alter cellular DNA. Conversely, the body blocks these short wavelengths in the skin and lens, leading to inflammation (sunburn) or opacity (cataracts) upon excessive exposure.
Sunlight, Mortality, and UV Reassessment
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(00:10:52)
  • Key Takeaway: Emerging research suggests that all-cause mortality is lower in individuals with high sunlight exposure, provided they avoid sunburn.
  • Summary: Dermatologists like Richard Weller are re-evaluating sunlight exposure, finding correlations between high sun exposure and lower all-cause mortality, specifically in cardiovascular disease and cancers. This research suggests avoiding sunburn is key, as skin cancer incidence is not always directly correlated with high Vitamin D levels or sun exposure.
Long Wavelengths and Mitochondrial Absorption
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(00:18:20)
  • Key Takeaway: Long-wavelength light’s positive effect on mitochondria is likely mediated by absorption in the surrounding water (nanowater), causing increased viscosity and faster ATP production spin rates.
  • Summary: Mitochondria themselves do not appear to absorb long-wavelength light; instead, the water environment surrounding them absorbs it. This absorption may decrease water viscosity, increasing the spin rate of the ATP-producing motor and also influencing the synthesis of more proteins involved in the energy pathway.
Light Penetration Through Body and Clothing
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(00:25:00)
  • Key Takeaway: Long-wavelength light penetrates the skin and bounces around internally, with only a few percent exiting the body, and it passes through standard clothing layers.
  • Summary: Experiments show that long-wavelength light is largely absorbed within the body after penetrating the skin, scattering throughout internal tissues. This light also passes through multiple layers of standard clothing without significant attenuation, indicating deep tissue exposure is possible.
Red Light Systemic Metabolic Effect
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(00:30:17)
  • Key Takeaway: A brief burst of red light shone on a small area of the back significantly reduced the blood glucose spike following a glucose tolerance test by over 20% in humans.
  • Summary: Inspired by observations in bumblebees, human trials showed that stimulating mitochondria with red light prior to consuming glucose lowered the subsequent blood sugar peak substantially. This systemic response occurred even when the light was applied to a small, localized area of the skin, suggesting mitochondrial communication across the body.
Red Light Mitigating Cell Death
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(00:36:19)
  • Key Takeaway: Long-wavelength light reduces the rate of cell death (apoptosis) in highly metabolic tissues like the retina and can offset degeneration in models of Parkinson’s disease.
  • Summary: By supporting mitochondrial health, long-wavelength light reduces the probability of mitochondria signaling cell death, which is a key driver of aging and disease. This effect was observed in the retina, where it preserved rod photoreceptors, and in primate models of Parkinson’s disease when light was applied abdominally.
Long Wavelength Light Through Skull
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(00:42:47)
  • Key Takeaway: Long-wavelength light passes through bone, including the skull, and can be used to measure and potentially influence mitochondrial function deep within the brain.
  • Summary: Long-wavelength light is not significantly blocked by bone, allowing it to pass through the skull. This property is being utilized in clinical settings, such as measuring light transmission through neonates’ heads to assess mitochondrial health in damaged brain tissue.
Retinal Aging and Vision Improvement
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(00:51:09)
  • Key Takeaway: Exposure to long-wavelength light (670 nm and above) improves color vision thresholds by about 20% in humans, an effect that is switched on by treatment and lasts for five days.
  • Summary: The retina has the highest metabolic rate in the body, making mitochondrial health critical for vision preservation. A three-minute exposure to 670 nm light resulted in a measurable improvement in color vision that persisted for five days across all tested subjects, suggesting a conserved evolutionary mechanism.
Long Wavelength Light Systemic Effects
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(01:01:06)
  • Key Takeaway: Long-wavelength light effects can spread systemically throughout the body, with local tissue responses occurring within hours and distal tissue responses taking up to 24 hours.
  • Summary: Long-wavelength light shining on one area, like the kneecap, causes a local effect within one to two hours, but the systemic message takes up to 24 hours to reach distant tissues like the hand. This systemic communication appears to involve changes in cytokine expression and microvesicles carrying cargoes throughout the serum. The speed and mechanism of this body-wide communication following localized light exposure are active areas of scientific investigation.
Short Wavelength Light Detriments
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(01:20:56)
  • Key Takeaway: Excessive exposure to short-wavelength (blue/violet) light from modern LED sources causes observable mitochondrial dysfunction, leading to systemic health detriments in animal models.
  • Summary: White light from LEDs is very short-wavelength enriched, causing mitochondria to decline in function, resulting in reduced ATP production and impaired breathing in real-time observation. Mice exposed to LED lighting exhibit increased weight gain, unbalanced blood glucose control, and behavioral changes indicative of chronic stress or infection. Furthermore, these mice developed fatty livers, smaller organs, and abnormal sperm morphology, highlighting serious systemic consequences.
LED vs. Sunlight Spectrum
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(01:31:54)
  • Key Takeaway: The primary issue with LED lighting is the heavy weighting toward short wavelengths and the absence of the smooth, balanced spectrum found in sunlight and incandescent bulbs.
  • Summary: Biological systems evolved under broad-spectrum light from sunlight and fire, which have a smooth spectral distribution; LEDs create a compressed, bumpy spectrum lacking sufficient long wavelengths to counterbalance the short wavelengths. Commercially available LEDs rarely mimic sunlight effectively by including wavelengths significantly beyond 700 nanometers due to cost and complexity. Mitochondria can detect the difference between a smooth incandescent spectrum and a compressed LED spectrum, suggesting balance, not just the presence of certain wavelengths, is key.
Incandescent Light Benefits
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(01:34:48)
  • Key Takeaway: Incandescent and halogen bulbs provide a solar-like, smooth spectrum that significantly improved color perception in subjects under LED-dominated environments, with benefits maintained for over a month.
  • Summary: The spectrum from incandescent bulbs is highly similar to sunlight, featuring a smooth transition across short, medium, and long wavelengths. Replacing harsh LED lighting with 40-watt incandescent desk lamps in windowless environments led to significant, sustained improvements in color perception for architectural model makers. This suggests that the built environment suppresses physiology via mitochondria, and full-spectrum, non-LED light sources can reverse these effects.
Myopia and Screen Light Concerns
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(01:48:03)
  • Key Takeaway: While the blue light in typical screens may not be the primary driver of mitochondrial harm, the absence of long-wavelength light combined with excessive close work is a major factor in the rising epidemic of myopia in children.
  • Summary: The blue light emitted by most computer screens (around 450nm+) is less concerning than the 420-440nm range, and direct screen exposure showed minimal effect on researchers in one study. However, the lack of long-wavelength light is a known driver of myopia, which causes the eye to elongate, leading to potential retinal tears and macular degeneration later in life. Interventions in Asia include physical barriers to increase reading distance and the use of red light, though lasers used in some treatments carry risks due to caustic light patterns.
Bringing Outdoors Indoors
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(01:56:33)
  • Key Takeaway: To counteract the negative effects of the built environment, it is critical to intentionally bring elements of the outdoors inside, such as through plant matter and full-spectrum/long-wavelength light sources.
  • Summary: Plant matter reflects infrared light, which can help balance the light environment, and planting trees has been shown to reduce systemic inflammation markers in urban populations. For those reliant on LED lighting, supplementing with low-cost, full-spectrum sources like dimmable halogen lamps or even candlelight in the evening can provide necessary long-wavelength exposure. This effort to restore natural light balance is viewed as a significant public health opportunity that can be implemented economically.
Mitochondrial Disease Intervention
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(02:05:06)
  • Key Takeaway: Long-wavelength light exposure provided dramatic, life-altering positive effects for a child with severe mitochondrial disease, demonstrating the malleability of mitochondria even in severe genetic disorders.
  • Summary: Children suffering from severe mitochondrial diseases, where ATP production is genetically disrupted, showed significant improvement after receiving long-wavelength light exposure. One child experienced a ‘gut-wrenching’ (positive) improvement in eyelid mobility (ptosis) within a month, leading to semi-mobility and the ability to walk to school. While the disease’s severity limits intervention success in some cases, this highlights the profound potential of light therapy to support mitochondrial function.
Mitochondrial Disease Patient Improvement
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(02:06:40)
  • Key Takeaway: A child with mitochondrial disease showed significant mobility improvement within a month following intervention, leading to emotional impact on researchers.
  • Summary: A child treated for mitochondrial disease experienced semi-mobility within about a month, evidenced by a video of the child walking to school. Researchers faced challenges recruiting enough children for the clinical trial due to the low density of severe cases in the UK. Dr. Jeffery suggests that even if the light intervention is ineffective, it poses no harm and wastes no money.
Upcoming Retinal Disease Trial
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(02:08:43)
  • Key Takeaway: A clinical trial for retinitis pigmentosa, a common retinal disease, is launching soon, focusing on changing patients’ light bulbs.
  • Summary: A trial for retinitis pigmentosa is imminent, funded by a US donor, with the next project focusing on changing light bulbs for these patients. Moorfields Eye Hospital, where Dr. Jeffery works, has a large ophthalmic population suitable for this study. Dr. Jeffery criticized the new hospital construction for blocking infrared light and installing poor-quality LEDs.
Host Appreciation and Research Shift
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(02:09:53)
  • Key Takeaway: Andrew Huberman praised Dr. Jeffery for shifting research focus to high-impact, low-cost public health applications related to light.
  • Summary: Andrew Huberman thanked Dr. Jeffery for traveling from the gray UK weather and for his meticulous, beautiful work over the years. Huberman noted that researchers often reach a juncture where they prioritize making the most positive impact, which Dr. Jeffery achieved by focusing on light’s effect on vision and mitochondrial health. Dr. Jeffery is commended for being vocal about actionable, low-cost suggestions for public health.
Podcast Support and Book Promotion
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(02:11:53)
  • Key Takeaway: Listeners can support the Huberman Lab podcast via zero-cost actions like subscribing, following, and leaving reviews on platforms.
  • Summary: Support for the podcast can be provided by subscribing on YouTube, following on Spotify and Apple, and leaving five-star reviews and comments on those platforms. Andrew Huberman is promoting his new book, “Protocols: an Operating Manual for the Human Body,” available for pre-sale at protocolsbook.com. He also encourages following Huberman Lab on all social media platforms for distinct science-related content.
Newsletter and Final Thanks
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(02:13:39)
  • Key Takeaway: The Neural Network newsletter offers free monthly summaries and detailed protocols on topics like sleep, dopamine, and fitness.
  • Summary: The Neural Network newsletter is a zero-cost monthly resource providing podcast summaries and one-to-three-page PDF protocols covering sleep optimization, dopamine, cold exposure, and fitness. Subscribers can sign up via the menu tab on hubermanlab.com, with assurance that emails are not shared. The segment concludes with a final thank you to Dr. Glen Jeffery for his participation.