Huberman LabDr. Glen Jeffery on Huberman Lab: Why LEDs harm mitochondria
Red and near-infrared wavelengths restore ATP in aging mitochondria; brief morning exposure blunts sugar spikes and slows vision decline with age.
CHAPTERS
- 3:00 – 12:00
Light Spectrum 101: Beyond What We See
Huberman and Jeffery define the visible and invisible portions of the light spectrum and how different wavelengths interact with the body. They distinguish ionizing UV from non‑ionizing visible/IR light and explain how UV is blocked by skin and eye tissues, while longer wavelengths penetrate more deeply.
- •Visible light spans roughly 400–700 nm (blue/violet to deep red); sunlight extends from ~300 nm UV to ~3000 nm infrared.
- •Short wavelengths (UV, violet, blue) carry high energy per photon and cause sunburn and DNA damage when excessive.
- •The skin and ocular media (cornea, lens) block most UV; this protects inner tissues but leads to conditions like snow blindness and cataracts with high exposure.
- •Cataract surgery with clear lenses increases blue light transmission; patients initially perceive excessive brightness and sparkliness, then the brain adapts.
- •Red, near‑infrared, and infrared carry less ‘kick’ per photon but penetrate tissues deeply and interact differently with biology.
- 12:00 – 31:00
Sunlight, UV, and Rethinking Skin Cancer Risk
They discuss emerging epidemiology suggesting that regular sunlight exposure reduces all‑cause mortality, particularly from cardiovascular disease and cancer, so long as sunburn is avoided. Dermatology’s traditional narrative of ‘sun equals skin cancer’ is challenged by data on vitamin D, melanoma sites, and population studies.
- •Dermatologist Richard Weller’s analyses show lower all‑cause mortality in people with higher sunlight exposure, with cardiovascular disease and cancers leading the benefit signal.
- •Sunburn and very high UV doses drive DNA mutations and non‑melanoma skin cancers; moderate exposure appears protective.
- •Most deadly melanomas are not directly linked to sun exposure and often arise on low‑sun areas (e.g., palms, soles, between toes).
- •Skin cancer patients often have low, not high, vitamin D, complicating the simple ‘sun equals cancer’ narrative.
- •Huberman advocates sunlight in eyes and on skin without burning, and flags large population studies (e.g., Sweden, East Anglia) that support benefit.
- 31:00 – 45:00
How Red and Infrared Light Power Mitochondria
Jeffery explains the modern understanding of how long‑wavelength light enhances mitochondrial ATP production by acting on nano‑structured water rather than directly on mitochondrial chromophores. He describes immediate increases in the ‘rotor’ speed of ATP synthase and longer‑term up‑regulation of respiratory chain proteins.
- •Early claims (e.g., by Tina Karu in Russia) that mitochondria absorb red light were hard to replicate with direct spectroscopy.
- •Water, not mitochondrial pigments, is the dominant absorber of long‑wavelength light; oceans appear blue because red/IR is absorbed.
- •Mitochondrial ATP synthase motors operate in nano‑water which is unusually viscous; long‑wavelength absorption reduces viscosity, increasing rotor spin and ATP output.
- •Over time, cells respond by increasing expression of electron‑transport‑chain proteins, effectively ‘laying down more tracks’ to carry higher electron flow.
- •This explains both acute and sustained benefits of red/near‑IR exposure and reconciles data across species.
- 45:00 – 1:06:00
Systemic Effects: Red Light, Blood Sugar, and Mitochondrial Signaling
Using bumblebees and humans, Jeffery’s group shows that brief red‑light exposure over a small skin area can blunt subsequent glucose spikes, while blue light worsens them. They interpret this as evidence that mitochondria act as a coordinated body‑wide network, relaying signals over hours via cytokines, microvesicles, and possibly mitochondrial transfer.
- •In starved bumblebees, red light reduced post‑glucose blood sugar rise, while blue light dramatically increased it.
- •In humans, 3–5 minutes of red light on a small back area before an oral glucose tolerance test reduced glucose spike magnitude by ~20%.
- •Subjects did not feel heat, and illumination covered a tiny fraction of body surface, indicating a systemic mitochondrial response.
- •Other labs show abdominal red light can reduce Parkinsonian symptoms in primates, presumably via reduced cell death in deep brain nuclei and systemic effects.
- •Mitochondria can induce or prevent apoptosis, secrete signals, alter cytokine profiles, and even be transferred between cells, supporting the view of mitochondria as a distributed communicating community.
- 1:06:00 – 1:25:00
Red Light for Vision: Aging Retina, Rods, and Macular Degeneration
They focus on the retina, an energy‑hungry tissue loaded with mitochondria, and show how long‑wavelength light can slow photoreceptor loss, sharpen color and low‑light vision, and potentially help conditions like age‑related macular degeneration—provided intervention occurs early in disease.
- •The retina has the highest metabolic rate in the body, with dense mitochondria, especially in rods; it ‘burns out’ like a sports car without servicing.
- •In mice, daily red‑light exposure slows age‑related loss of rod photoreceptors; similar protective effects are seen across species.
- •In humans, a single 3‑minute exposure at ~670 nm (torch/flashlight near the eye, eyelids open or closed) improves color thresholds ~20% in most older adults, with effects lasting ~5 days.
- •Response is stronger in older individuals whose mitochondria have more room for improvement; some younger people still show robust gains.
- •Attempts to treat established macular degeneration largely failed when disease was advanced; replication with earlier‑stage patients showed benefit.
- •Red/near‑IR is best seen as slowing aging and disease progression rather than reversing advanced, structurally destructive stages.
- 1:25:00 – 1:35:00
Timing and Dose: Morning Advantage and ‘Switch‑Like’ Responses
They discuss circadian modulation of mitochondrial behavior and how it shapes response to red/near‑IR light. Mitochondria change their protein composition and functional priorities across the day, making morning the optimal window for photobiomodulation.
- •Mitochondrial composition and activity vary across 24 hours; they are not the same organelles at 9 a.m. and 4 p.m.
- •Morning (pre‑sunrise to ~11 a.m.) is when ATP production is maximal and red‑light interventions yield the largest functional improvements.
- •In fly/mouse/human data, red‑light benefits on vision and mitochondrial function are robust in the morning and hard to elicit in the afternoon.
- •Red‑light response is ‘switch‑like’: once a minimum dose threshold is passed, more intensity or duration does not linearly increase benefit.
- •Over time, labs discovered effective energies dropping from ~40 mW/cm² to ~8 and even ~1 mW/cm², indicating high sensitivity; very bright devices are not necessary.
- 1:35:00 – 1:49:00
Penetration Depth: Through Skin, Bone, and the Brain
Jeffery details experiments showing that long‑wavelength light passes through skin, clothing, and even bone with surprisingly little attenuation, scattering extensively inside the body. This underpins both therapeutic opportunities (e.g., brain, organs) and clinical monitoring techniques using transcranial near‑IR.
- •Radiometer and spectrometer readings show a few percent of long‑wavelength sunlight exits the back of a person facing the sun; the vast remainder is absorbed internally after high‑order scattering.
- •Typical T‑shirt fabric (multiple layers, any color) transmits significant red/near‑IR, though rubber and similar materials block it.
- •Near‑IR light passes through bone; images of hands illuminated from one side show vasculature but not bones, confirming bone transmission and hemoglobin absorption.
- •Audiology and neonatal researchers use red/near‑IR transmission through the head to monitor brain mitochondrial function and prognosticate outcomes after neonatal stroke.
- •Clinicians and ethic boards consider this very safe because these are non‑ionizing, low‑energy wavelengths, unlike UV or X‑rays.
- 1:49:00 – 2:06:00
Indoor LEDs: Mitochondrial Damage, Metabolic Dysfunction, and Fertility Effects
They pivot to modern LED lighting and describe convergent evidence from animals that blue‑shifted, red‑depleted lighting disrupts mitochondrial function across tissues. Consequences include retinal decline, obesity, fatty liver, altered anxiety‑like behavior, organ shrinkage, and reduced sperm quality.
- •Standard white LEDs, even ‘warm’ ones, have a strong narrow blue spike around 420–440 nm and almost no emission beyond ~700 nm.
- •In mouse retinas under LED lighting, mitochondrial membrane potential drops and responsiveness declines at energy levels mimicking domestic/office environments.
- •Flies under blue‑rich light show shortened lifespan; mice gain weight, develop poor glucose control, and show behavior consistent with chronic low‑level infection/inflammation.
- •Upcoming data show LED‑lit mice develop fatty liver, elevated liver distress markers (e.g., ALT), smaller livers, kidneys, and hearts, and impaired sperm motility and morphology.
- •Jeffery emphasizes the critical role of balance: mitochondria evolved under broad, smooth solar spectra; strong short‑wavelength stimulation without long‑wavelength counterbalance appears pathological over time.
- 2:06:00 – 2:19:00
Architecture, Glass, and the ‘Double Hit’ on Health
They explore how building design amplifies the LED problem by excluding beneficial infrared from sunlight. Cheap, narrow‑spectrum LEDs and IR‑blocking glass combine to create indoor environments that are spectrally alien to human evolution.
- •Lighting is typically the last budget line in a build, so cost pressures push architects and owners to install the cheapest LED fixtures, which are spectrally poor.
- •Commercial glazing often blocks infrared to improve energy efficiency, preventing solar IR from reaching interior spaces.
- •Jeffery labels this combination—a blue‑heavy artificial spectrum plus IR‑blocking windows—a ‘double hit’ to mitochondrial health.
- •Architects at major firms now consult him to design ‘healthy lighting’ for large projects (e.g., hospitals), exploring ways to reintroduce more red/IR.
- •Even supposedly ‘sunlike’ consumer LEDs rarely emit meaningfully beyond ~700 nm; achieving a true smooth full spectrum would require many LEDs and high power, which is impractical and still not equivalent to sunlight.
- •Mitochondria can distinguish between a smooth incandescent/solar spectrum and a stack of discrete LEDs; blended LEDs don’t reproduce the same biological effects.
- 2:19:00 – 2:31:00
Low‑Cost Solutions: Halogen Bulbs, Plants, and Behavioral Tweaks
The conversation turns practical: how to offset LED damage in realistic settings. Jeffery offers strategies for individuals and institutions that cost little, often saving money in the long term by improving health and reducing absenteeism.
- •Halogen bulbs are a type of incandescent with a smooth, sun‑like spectrum, including abundant infrared; they are still available in some markets and required where LEDs fail (e.g., ovens).
- •Dimmed halogens still emit plenty of IR and last much longer, limiting energy and replacement costs.
- •In a UCL building with windowless, harsh LED‑lit rooms, giving staff 40‑W incandescent desk lamps pointing down (no direct eye exposure) for two weeks produced large improvements in color perception; these gains persisted for at least a month after lamps were removed.
- •Outdoor plants and trees reflect infrared light; planting around buildings increases local IR and correlates with reduced systemic inflammation markers in nearby residents.
- •Studies where cities planted thousands of trees found later reductions in stress‑related blood biomarkers (e.g., complement proteins), suggesting health benefits of increased environmental IR and greenery.
- •A simple mantra: get a dog (to force daily outdoor walks), put a halogen lamp in the kitchen or workspace (especially for morning light), keep windows untinted where possible, and add plants inside and outside.
- •Candlelight and beeswax candles provide long‑wavelength‑rich light but are dim and must be used safely; they can modestly supplement IR in the evening.
- 2:31:00 – 2:44:00
Children, Myopia, and Screens: Special Vulnerabilities
Jeffery distinguishes between spectral and behavioral issues in children: while most screens emit longer‑wavelength blue and may be less directly toxic to mitochondria than feared, excessive near work plus red‑depleted environments are driving a myopia epidemic with serious long‑term retinal consequences.
- •Typical phone/computer screens use relatively longer‑wavelength blue (~450+ nm), likely less damaging than the 420–440 nm peak in many LEDs.
- •Pediatric ophthalmologists are more concerned about prolonged close work and reduced outdoor time, which both correlate strongly with myopia.
- •High myopia stretches the retina; in mid‑ to late life, this increases risk of tears and macular degeneration‑like pathology.
- •China’s response includes physical desk bars preventing kids from bringing text too close and experimental red‑light interventions—some flawed by using lasers, which create dangerous high‑energy ‘caustic’ hotspots in tissue.
- •Jeffery strongly warns against lasers for routine use; unlike LEDs, laser light doesn’t scatter evenly and can create unseen toxic peaks in tissue energy.
- •He advocates windows, outdoor time, and possibly halogen/incandescent supplementation in classrooms, emphasizing early prevention rather than late‑stage treatment.
- 2:44:00
Clinical Frontiers: Mitochondrial Disease, Retinitis Pigmentosa, and Nursing Homes
They close with early but compelling clinical stories: children with mitochondrial diseases showing striking functional gains with red light, trials in retinal degenerations, and the prospect of simple bulb changes in nursing homes and ICUs to accelerate recovery and preserve function.
- •Mitochondrial diseases caused by mtDNA defects substantially impair ATP production; some affected children are bedridden and die young from heart failure and other complications.
- •Families reached out after hearing about red light and mitochondria; although Jeffery lacked formal ethics to prescribe, some who tried red‑light protocols at home reported dramatic improvements, such as a previously ptotic child gaining eyelid control and semi‑mobility within a month.
- •A formal mitochondrial‑disease trial in the UK struggled due to low patient density and severe illness in many candidates; funding will be returned, illustrating logistical challenges.
- •Ongoing trials in retinitis pigmentosa (RP) using red light have been funded; next steps include changing home light bulbs for RP patients at Moorfields Eye Hospital to test environmental effects.
- •Jeffery argues red/IR is extremely unlikely to harm and may be beneficial in these populations; he encourages low‑cost environmental interventions (e.g., bulbs) as a rational starting point.
- •He highlights nursing homes and ICUs as high‑value targets for light reform—e.g., wheeling patients into IR‑rich spaces for meals and using incandescent/halogen sources to support mitochondrial function and speed discharge.
- •He criticizes plans for new, glass‑walled hospitals with IR‑blocking glass and cheap LEDs, calling for health‑centric lighting standards.
