The One Overlooked Factor That Predicts Heart Disease, Cancer & Dementia | Dr. Roger Seheult

This podcast features Dr. Roger Seheult, a pulmonary, critical care, and sleep specialist, discussing the profound yet overlooked impact of natural sunlight, specifically its full spectrum including infrared light, on overall health. Dr. Seheult explores the science behind how light absorbed through the skin and eyes influences mitochondrial function, immunity, and chronic diseases such as heart disease, cancer, dementia, and diabetes. The conversation highlights the detrimental effects of modern lifestyle changes on sunlight exposure and introduces practical approaches for optimizing one's "light diet" to improve physiological and cognitive health.

The Spectrum of Sunlight and Its Biological Impact

Dr. Seheult explains that sunlight is a continuum of electromagnetic radiation, encompassing visible light as well as invisible ultraviolet (UV) and infrared (IR) light. UV light, particularly UVB, is essential for the skin's production of vitamin D, a well-known nutrient critical for many physiological functions. Contrastingly, infrared light has a much lower frequency and longer wavelength, which enables it to penetrate deeply through skin, clothing, and even bone. Infrared light reaches into the body, directly affecting cells and mitochondria by upregulating their function. This insight challenges the conventional belief that light's primary biological role is limited to the eyes and skin surface.

Infrared Light and Mitochondrial Health

A core focus of the discussion is the effect of infrared light on mitochondria, the "batteries" of the cells responsible for energy production. Citing recent studies, including one from University College London, Dr. Seheult describes how infrared light exposure improves mitochondrial function by enhancing electron transport chains and increasing energy output, which is critical for cellular metabolism. Improved mitochondrial function correlates with better health outcomes and may help prevent and mitigate chronic diseases such as heart disease, diabetes, cancer, dementia, inflammation, and infectious diseases like COVID-19. This deeper understanding of photo-metabolism reveals an emerging frontier in health that integrates quantum mechanics, biochemistry, and photobiology.

Cognitive Decline and Neurodegenerative Disease

Dr. Seheult connects the benefits of sunlight exposure to brain health, noting the importance of maintaining healthy mitochondria in neural tissue. Infrared light can penetrate the skull and activate mitochondria in brain cells, especially in the gray matter, which supports cognitive functions such as color perception and memory. He discusses evidence linking mitochondrial dysfunction in the brain to neurodegenerative diseases like Alzheimer's and Parkinson's. The alignment of circadian rhythms with natural light also plays a vital role in preserving cognitive function and mood.

Lessons from the COVID-19 Pandemic

During the pandemic, Dr. Seheult recounts how initial focus on vitamin D status led to mixed outcomes in patient treatment. Subsequent studies revealed that latitude and sunlight exposure correlated more closely with COVID-19 outcomes than vitamin D levels alone. Research showed that ultraviolet A (UVA) exposure, a part of sunlight distinct from the UVB required for vitamin D synthesis, was associated with reduced COVID-19 mortality across different regions. Inspired by these insights and a Brazilian study using LED infrared light therapy for hospitalized COVID-19 patients, Dr. Seheult initiated sunlight exposure protocols for seriously ill patients. Anecdotes describe rapid improvement in oxygen requirements and recovery times, supporting the hypothesis that natural sunlight, in all its spectral complexity, contributes significantly to immune modulation and healing.

Sunlight and Inflammatory Response

The podcast delves into the molecular mechanisms by which infrared light modulates inflammation. Infrared exposure decreases the activity of toll-like receptor 4, a key mediator of inflammatory cytokine production. This reduction in inflammatory signaling, including important molecules like tumor necrosis factor-alpha and interleukins, helps to mitigate the excessive immune responses responsible for complications like pneumonia and severe viral infections. This anti-inflammatory effect, combined with enhanced mitochondrial energy production, forms a powerful therapeutic avenue supporting recovery and resilience.

The Role of Modern Technology and Lifestyle

Dr. Seheult highlights the unintended consequences of technological and urban development on sunlight exposure. Modern climate control systems, low-emissivity window glass, and widespread use of LED lighting significantly reduce infrared light indoors, fundamentally altering the light environment humans evolved with. These innovations, designed for energy efficiency and comfort, inadvertently deprive people of the beneficial wavelengths of light necessary for optimal mitochondrial and immune function. Additionally, the prevalence of indoor living, sedentary behavior, and the impacts of pandemic-related lockdowns have further diminished consistent access to natural sunlight.

The Seasonal Pattern of Disease and Sunlight Correlation

An important epidemiological insight covered in the discussion is the seasonal fluctuation in mortality and disease prevalence aligned with changing sunlight exposure. Death rates from heart disease, cancer, dementia, influenza, and other respiratory illnesses peak 1 to 3 weeks following the shortest day of the year, when sunlight is minimal, then decline after the longest day of the year when sunlight exposure is maximal. This pattern transcends geographic regions and contradicts common explanations attributing seasonal illness solely to indoor crowding. Comparisons with the southern hemisphere and regions near the equator further validate sunlight as a critical factor in disease susceptibility and immune competence.

Historical Perspectives on Sunlight Therapy

Dr. Seheult provides historical context by discussing the treatment approaches during the 1918 Spanish flu pandemic and earlier medical practices. Sanitariums focused on fresh air, sunlight, and hydrotherapy often had better patient outcomes than traditional hospitals, which used pharmaceuticals that suppressed fever and possibly impaired immune responses. Early recognition of sunlight's healing properties, notably at the Battle Creek Sanitarium, predated the discovery of germs and antibiotics. These lessons underscore the long-standing but overlooked importance of natural environmental factors in promoting health and fighting infections.

Integrating Laws of Health

The conversation situates sunlight within a broader framework of eight fundamental laws of health encompassing nutrition, exercise, hydrotherapy, temperance (avoiding harmful substances like tobacco and excessive alcohol), fresh air, rest (including sleep hygiene and darkness at night), sunlight, and spiritual connection. Dr. Seheult emphasizes that chronic diseases result largely from violations of these principles. He advocates a holistic approach combining these laws, rather than relying solely on medications, while warning against prematurely stopping prescribed therapies without medical supervision.

Practical Recommendations for Sunlight Exposure

Dr. Seheult advises that people deliberately increase their daily sunlight exposure by at least 15 minutes when possible, emphasizing that infrared light penetrates clothing and can be received even in the shade. If morning outdoor exposure is not feasible, he recommends using a 10,000 lux bright light lamp for 15 minutes to support circadian rhythms and mood, although such lamps lack infrared light and hence do not provide full mitochondrial benefits. He notes that mundane behaviors such as eating lunch outdoors can also mitigate afternoon energy slumps by leveraging sunlight's metabolic effects. Additionally, he discusses innovations like wearable devices with light sensors to track personal light exposure and apps such as shadowmap.org that help consumers assess sunlight availability at various locations.

Considerations Regarding Artificial Lighting and Red Light Therapy

The podcast addresses the pros and cons of artificial light sources. Modern LED bulbs emit narrow bands of visible light without infrared wavelengths and often flicker in ways that may cause physiological stress. In contrast, incandescent bulbs emit a broader spectrum closer to natural sunlight, including beneficial infrared light. Dr. Seheult personally reintegrates incandescent bulbs into his home lighting to capture these advantages. He cautions about the biphasic dose response of red and infrared light therapy devices, where excessive use can negate benefits or cause harm. Thus, while red light therapy shows promise for specific clinical applications, it cannot replace the complex, broad-spectrum light delivered by the sun.

Nighttime Light Exposure and Melatonin

The conversation also covers the importance of minimizing exposure to artificial light at night to preserve melatonin production and maintain healthy sleep patterns. Dr. Seheult recommends reducing overhead lighting and using blue light-blocking glasses as a secondary measure if darkness is not possible. He points out that melatonin suppression occurs with most light sources, regardless of spectrum, underscoring the value of darkness for restorative rest.

The "Scurvy" Analogy for Sunlight Deficiency

Dr. Seheult closes with an analogy comparing modern-day chronic disease and health decline due to lack of natural sunlight to the historical condition of scurvy caused by vitamin C deficiency among sailors. Just as the simple addition of vitamin C-rich foods corrected scurvy, restoring regular exposure to natural sunlight—previously abundant but now systematically removed from many people's lives—is poised to reverse a broad spectrum of health issues. This metaphor highlights the fundamental yet overlooked role of natural sunlight as a critical nutrient in human health.