The Power of Light Therapy: Sunlight, Red Light, Mitochondria & Longevity | Prof. Glen Jeffery

In this episode of Live Longer World, host Aastha Simes welcomes Professor Glen Jeffery, a leading researcher investigating the profound impact of light on human health, metabolism, and aging. While discussions around health often revolve around diet, exercise, and sleep, this conversation delves into the often-overlooked influence of light – encompassing sunlight, artificial light, blue light, and red/infrared light. Professor Jeffery shares insights from his cutting-edge research, revealing how different wavelengths of light interact with our cellular machinery, particularly mitochondria, affecting everything from blood glucose levels to the aging process. The episode transitions from the underlying science to practical, actionable advice for listeners seeking to optimize their health through conscious light exposure.

Core Messages

• Light is a Critical, Understudied Health Factor: Beyond vision and plant photosynthesis, light (both natural and artificial) significantly impacts human physiology, particularly mitochondrial function and metabolism, yet this is often overlooked in biological and medical fields.
• Red vs. Blue Light - A Mitochondrial Tug-of-War: Very simplistically, red and near-infrared light (approx. 670-900nm) tend to "recharge" mitochondria, boosting their energy production (ATP). Conversely, specific blue light wavelengths (especially ~420-450nm, prominent in LEDs) can "discharge" mitochondria, reducing function and potentially contributing to metabolic issues and aging.
• Morning Exposure is Key for Red Light Benefits: The positive effects of red/infrared light exposure on mitochondria are most pronounced when received in the morning (roughly between sunrise and 11 AM). Afternoon exposure shows significantly diminished effects, likely due to mitochondrial circadian rhythms and differing functions throughout the day.
• Modern LEDs Pose a Health Challenge: The shift from sunlight, fire, and incandescent bulbs (rich in red/infrared) to LED lighting (often lacking infrared and having spikes in potentially harmful blue light) represents a significant environmental change with potential negative consequences for mitochondrial health, metabolism (e.g., glucose regulation), and aging.
• Sunlight Offers a Balanced Spectrum: Sunlight provides a natural, evolutionarily tuned balance of different light wavelengths. While targeted red light can offer benefits, sunlight (or lighting mimicking it, like incandescent bulbs) may be superior due to this spectral balance. Concerns about sunlight's dangers might be context-dependent and potentially overstated compared to its benefits for overall disease prevention.
• Simple, Low-Dose Interventions Can Be Effective: Significant benefits from red light don't require high power or long duration. Short exposures (e.g., 3 minutes) of low-intensity red/infrared light in the morning can be sufficient to trigger positive effects. Exposing even a part of the body can lead to systemic benefits due to mitochondrial signaling.
• Distinguishing Blue Light Impacts: It's crucial to differentiate between the blue light wavelengths potentially harmful to mitochondria (~420-450nm spikes in LEDs) and the blue light that primarily affects the circadian system and sleep (~460-480nm, impacting retinal cells). Professor Jeffery expresses skepticism about the mitochondrial benefits of blue-light-blocking glasses based on his research.

The Underappreciated Role of Light in Health

Professor Jeffery describes his research journey from neuroscience towards public health, focusing on how the light environment affects the population. He notes a significant disconnect: while biologists and medics often compartmentalize light's role to vision or plants, architects and lighting engineers are far more receptive to the idea that light directly impacts overall health. The medical community's protocol-driven approach often hinders the adoption of novel concepts like light therapy, whereas architects, potentially concerned about the health implications of building design, show more interest. Professor Jeffery emphasizes that light research, particularly concerning its systemic effects on the body via mitochondria, is grossly understudied.

Understanding Red and Blue Light: Impact on Mitochondria

Professor Jeffery explains the relevant light spectrums. "Red light" in his research context spans from visible red (~670nm) deep into the near-infrared (up to ~900nm), which is invisible. He often works with 850nm. "Blue light," particularly the potentially damaging wavelengths, falls in the deep blue/violet range (~420-450nm). He offers a simple analogy: mitochondria are like cellular batteries. Red/infrared light helps recharge these batteries, increasing their potential and ATP (energy currency) production. Conversely, specific blue light wavelengths drain the batteries, reducing potential and ATP output. This differential impact forms the basis for understanding light's effects on metabolism and disease.

The Benefits and Nuances of Red Light Therapy

The conversation explores various demonstrated and potential benefits of red/infrared light, primarily linked to improved mitochondrial function:

• Blood Glucose Regulation: Professor Jeffery's research shows that pre-exposure to red light (specifically 670nm) before a glucose challenge significantly reduces the subsequent blood sugar spike in healthy individuals and those with type 2 diabetes. This occurs because stimulated mitochondria increase their demand for glucose, drawing it from the bloodstream.
• Wound Healing: Although not his direct research, Jeffery acknowledges established evidence (including NASA studies) that red light accelerates wound healing and reduces scarring.
• Retinal Health: Early work on age-related macular degeneration (AMD) showed promise, though initial trials faced challenges. Newer trials focusing on earlier disease stages are yielding positive results. The principle is that boosting mitochondrial function in the high-energy-demand retina can slow degenerative processes.
• Neurodegenerative Diseases: Potential benefits are being explored by others in conditions like Parkinson's disease, where mitochondrial dysfunction is implicated.
• Mitochondrial Diseases: Professor Jeffery shares compelling anecdotal evidence from work with children suffering from mitochondrial diseases, where red light therapy led to dramatic improvements in energy levels and mobility in some cases.
• COVID-19: Some studies, particularly from South America, suggested benefits of long-wavelength light therapy for hospitalized COVID patients (e.g., improved oxygenation, reduced critical care time), though the pandemic's pressures hindered wider investigation.

Key practical aspects emerged:

• Timing is Crucial: The beneficial effects are primarily seen with morning exposure (approx. sunrise to 11 AM). Afternoon applications are largely ineffective.
• Dose is Not Linear: It acts like a switch; exceeding a certain threshold yields no additional benefit. Short durations (around 3 minutes) are sufficient. High power is unnecessary and potentially wasteful; low energy levels work. Jeffery warns against companies marketing overly powerful, expensive devices.
• Systemic Effects: Exposing even a small area of the body can trigger systemic mitochondrial responses, albeit potentially with a delay (e.g., 24 hours) compared to whole-body exposure. Infrared light penetrates clothing (like cotton, but not rubber) and even bone.
• Wavelength Choice: While 670nm works, Jeffery often uses 850nm as it penetrates deeply and is invisible, making it less intrusive for interventions (e.g., in workplaces or nursing homes).

Professor Jeffery emphasizes that red light is generally not a cure but can act as a powerful supportive therapy or "sticking plaster," particularly valuable when other options are limited. He feels confident about its safety profile, as it utilizes wavelengths naturally present in sunlight.

The Hidden Dangers of Modern Blue Light Exposure

The widespread adoption of LED lighting since the early 2000s presents a unique environmental stressor. Unlike sunlight, fire, or incandescent bulbs (which have a broad spectrum including ample red/infrared), LEDs are engineered for energy efficiency, primarily emitting light within the visible spectrum. Critically, they often lack significant red/infrared components and possess sharp peaks in the blue range, particularly around 420-450nm. This specific blue light actively suppresses mitochondrial function (reduces membrane potential and ATP production). Professor Jeffery highlights several lines of evidence:

• Astronaut Health: Studies on astronauts on the International Space Station (ISS), living under predominantly LED lighting for extended periods, revealed increased rates of pre-diabetes and signs of premature aging – outcomes linked to mitochondrial dysfunction.
• Gulf Countries & Diabetes: Regions like Qatar and Saudi Arabia have extremely high diabetes rates. Their populations spend vast amounts of time indoors under LED lighting, often behind infrared-blocking glass (to manage heat), further limiting beneficial long-wavelength light exposure.
• Animal Studies: Mice exposed primarily to LED lighting show increased weight gain (as glucose isn't efficiently used by mitochondria and gets stored) and impaired insulin regulation.
• Physiological Effects: Exposure to the specific blue wavelengths found in LEDs can cause near-instantaneous changes in blood pressure (lowering it) and heart rate (increasing it), indicating direct systemic impact.

The concern is the chronic, low-level mitochondrial stress imposed by ubiquitous LED lighting in homes, offices, and public spaces, potentially contributing to metabolic diseases and accelerated aging, especially in sedentary indoor populations.

Sunlight: The Original and Optimal Light Source?

Professor Jeffery argues that since life evolved under sunlight, its balanced spectrum is likely optimal for health. His experiments comparing targeted red light wavelengths to broad-spectrum incandescent light (which closely mimics sunlight) showed *better* results with the incandescent source. This suggests the combination of wavelengths in sunlight might be more beneficial than isolated red light supplementation. Key points regarding sunlight:

• Balance is Key: Sunlight contains both blue and red/infrared light in a natural ratio. Isolating blue light (as in LEDs) makes it problematic; isolating red light offers benefits, but the full spectrum might be ideal.
• Sunlight Benefits vs. Risks: While excessive UV exposure carries risks (skin type and location dependent), population data consistently links greater sunlight exposure to lower rates of cardiovascular disease, diabetes, and even some cancers. Jeffery suggests the fear of sunlight might be somewhat overblown, citing research questioning the direct causality for certain skin cancers and noting the low cancer rates in sun-adapted indigenous populations.
• Practical Considerations: Infrared light penetrates clouds effectively, so cloudy days still offer these wavelengths. It also passes through typical window glass (unless specifically IR-blocking) and clothing like cotton. Morning sunlight exposure appears particularly valuable. The required duration is unknown, but likely more than brief moments.

The implication is that maximizing safe, natural sunlight exposure, especially in the morning, is a foundational health practice. Where this is impractical, using full-spectrum lighting like incandescent bulbs is a better alternative to standard LEDs.

Mitochondria: The Cellular Powerhouses at the Core

The discussion underscores the centrality of mitochondria to health and aging. These organelles, originating from symbiotic bacteria, are responsible for producing the vast majority of the body's energy (ATP) – generating roughly our body weight in ATP each day. Their function is critical not just for energy, but they also play key roles in signaling pathways, including initiating programmed cell death (apoptosis) when severely damaged. Mitochondrial decline is a hallmark of aging and is implicated in numerous chronic diseases (neurodegeneration, diabetes, cardiovascular disease). The recent discovery of high melatonin concentrations *within* mitochondria adds another layer of complexity; this melatonin likely acts as a potent local antioxidant, protecting mitochondria from excessive damaging reactive oxygen species (ROS) they naturally produce.

Practical Applications and Future Directions

Professor Jeffery translates the science into actionable advice:

• Prioritize morning sunlight exposure.
• Replace LED bulbs with incandescent bulbs, especially in areas used frequently in the morning (like kitchens).
• If using red light therapy devices: use them in the morning, for short durations (e.g., 3 minutes), choose devices emitting around 670nm or 850nm, and avoid overly powerful or expensive models.
• Be aware of the potential downsides of ubiquitous LED lighting and IR-blocking windows.
• Professor Jeffery found no benefit from blue-light-blocking glasses in his experiments targeting mitochondrial function or vision metrics, though acknowledges they might help with sleep regulation (a circadian effect mediated by different blue wavelengths and pathways). He also believes screen-emitted blue light primarily impacts the circadian system, not mitochondria directly.
• Firelight offers a spectrum similar to sunlight and has deep evolutionary roots.

Looking forward, Professor Jeffery emphasizes the need for greater public awareness and communication. He now dedicates significant effort to translating this science for the public, answering emails, and collaborating with architects to create healthier built environments. He sees immense potential in simple light-based interventions for improving public health, particularly in clinical settings and nursing homes.

Conclusion

This episode powerfully argues that light is a fundamental, yet often ignored, pillar of health, operating largely through its effects on mitochondria. Professor Glen Jeffery's research highlights the potential benefits of harnessing red and near-infrared light, particularly from sunlight or sunlight-mimicking sources like incandescent bulbs, especially in the morning. Conversely, it raises significant concerns about the chronic mitochondrial stress potentially induced by modern LED lighting. The core message is that by understanding and consciously managing our light environment – seeking natural sunlight, choosing appropriate artificial lighting, and potentially using targeted red light therapy judiciously – we can significantly support our mitochondrial health, metabolism, and potentially slow aspects of the aging process. Simple changes in lighting and daily habits could offer profound health benefits.