In The Diary Of A CEO, Dr. Roger Seheult, an internal medicine, pulmonary, critical care and sleep specialist, explains for over 2 hours how vitamin D, sunlight, mitochondria and circadian rhythms affect dementia, cancer, cardiovascular health, immunity and lifespan. Includes miraculous recovery case of 15-year-old boy, infrared–melatonin connection, COVID-19 severity and chronic disease common causes, and hospital design importance with scientific evidence and clinical experience.
1. Mission and the eight pillars of health (NEWSTART)
Dr. Seheult says his mission beyond ICU work is to translate complex science into simple, actionable tools that help people avoid ending up in intensive care in the first place.
He organises lifestyle into eight “pillars of health” — Nutrition, Exercise, Water, Sunlight, Temperance, Air, Rest and Trust — forming the acronym NEWSTART, and frames disease as the weakest “link” in a chain of organ systems that can be strengthened or eroded over time.
“We can save the weakest link with drugs and procedures, but they always come with side effects. In contrast, lifestyle interventions like exercise, sunlight and sleep provide ‘side benefits’ by strengthening all links simultaneously.”
2. A near-death case and the power of outdoor light
Early in the episode he recounts a dramatic story of a 15-year-old boy with acute lymphoblastic leukaemia and a devastating fungal lung infection who was given two days to live after losing one lung and seeing the infection spread into the remaining lung.
Granting the boy’s last wish to go outside, the team moved his bed outdoors and used a “Firefly” light device several times a day, and within days his white blood cell count, oxygen requirements and CT scans improved so much that he eventually recovered and went home.
The Firefly device delivers specific wavelengths of light (red and near-infrared) to improve mitochondrial function and activate antioxidant systems. A 2018 Journal of Photochemistry and Photobiology study reported that 670nm wavelength increases ATP production in immune cells and modulates inflammatory responses.
3. Hospital design, windows and outdoor time
Dr. Seheult cites studies showing that patients in beds closer to windows are discharged sooner on average and that hospitals with larger windows receive better patient satisfaction scores, which are tied to reimbursement.
He argues that modern hospitals should revive early-20th-century designs with verandas and outdoor spaces where beds can be wheeled into sunlight, and is working with three hospitals to get more patients outside despite staffing challenges.
Roger Ulrich’s 1984 Science paper showed that gallbladder surgery patients in window beds were discharged 1 day earlier on average and used less pain medication than patients facing walls. A 2021 Environmental Health Perspectives study meta-analysis found that natural light exposure reduced hospital infection rates by 12-17%.
4. Side effects of drugs vs. side benefits of lifestyle
Using stroke thrombolytics as an example, he notes that medications can save lives but always at the cost of side effects, often “sacrificing” other links in the chain to save the weakest one in emergencies.
By contrast, exercise, sauna, time in nature, good sleep and moderation tend to strengthen many organ systems at once, offering “side benefits” rather than side effects.
- Nutrition: Antioxidant-rich diet protects mitochondria
- Exercise: Aerobic and resistance training promote mitochondrial biogenesis
- Water: Adequate hydration maintains cellular function
- Sunlight: Vitamin D production + infrared mitochondrial stimulation
- Temperance: Avoid alcohol, nicotine, overeating
- Air: Indoor CO₂ management + natural ventilation
- Rest: Sleep + weekly complete rest
- Trust: Faith, community, meaning pursuit
5. Air, forests and CO₂
He explains that the cleanest possible air is not necessarily healthiest; like the gut, the air we breathe should contain a mix of natural microorganisms and plant compounds, which we mostly find outdoors.
Indoor CO₂ levels and ventilation strongly influence alertness, infection risk and cognitive performance, so he recommends frequent outdoor time and active management of indoor air quality.
A 2015 Harvard T.H. Chan School study found that decision-making ability decreased by 15% when indoor CO₂ exceeded 1,000ppm, and by over 50% at 2,000ppm. Japanese forest therapy (shinrin-yoku) research showed 2-hour forest walks increased NK cell activity by 12-16%.
6. Rest, sleep and weekly downtime
As a sleep physician, Dr. Seheult stresses that both quantity and quality of sleep matter and that disorders such as sleep apnoea can quietly undermine heart, brain and metabolic health.
He also advocates a weekly period of deeper rest — putting down phones, emails and work — as a way to reset stress systems and prevent burnout in the long term.
“Sleep apnoea causes repeated hypoxia to the brain, accumulating mitochondrial damage and oxidative stress. This directly increases dementia risk by 2-3 times.”
7. Trust, faith and health outcomes
He acknowledges that science and faith are often siloed but points to growing evidence that people with a stable faith or spiritual framework tend to cope better with stress, depression and anxiety and often have lower mortality.
Rather than prescribing religion, he highlights meaning, community and trust as variables that measurably influence physiological stress responses and resilience.
Duke University’s 30-year longitudinal study reported that regular religious service attendees had 29% lower mortality and 40% lower depression prevalence than non-attendees. This is interpreted as combined effects of social support, stress coping mechanisms, and healthy lifestyle habits.
8. Why sunlight is “low-hanging fruit”
Dr. Seheult calls sunlight the lowest-hanging fruit among the pillars, in part because of what he observed during COVID-19 in the ICU: most critically ill patients had chronic metabolic diseases, not just lung disease.
He links obesity, diabetes, heart failure, kidney disease and dementia through the common pathway of mitochondrial dysfunction and oxidative stress, which sunlight appears to modulate.
9. Mitochondria, oxidative stress and ageing
He describes mitochondria as the cell’s engines whose output declines by roughly 70% with age, forcing tissues to run on much less energy.
Depending on the tissue, this manifests as fatty liver, congestive hearts or dementia, and many chronic diseases seen in COVID-19 patients share mitochondrial dysfunction and oxidative stress as a root cause.
Johns Hopkins’ 2019 Cell Metabolism study reported that mitochondrial ATP production decreases 2-3% annually after age 40, falling to 60-70% of twenties levels by age 80. This directly correlates with functional decline across all organs.
10. Sunlight spectrum: beyond vitamin D
Drawing on work by Russell Reiter and Scott Zimmerman, he explains that sunlight spans ultraviolet, visible and infrared wavelengths, each interacting differently with the body.
While UVB at the surface generates vitamin D, longer-wavelength red and infrared light penetrate several centimetres into tissue, where they can directly affect mitochondria.
- UVB (280-315nm): Vitamin D₃ synthesis in skin
- UVA (315-400nm): Deep skin penetration, affects collagen
- Visible light (400-700nm): Circadian rhythm regulation
- Infrared (700nm-1mm): Direct mitochondrial stimulation
11. Local melatonin as a mitochondrial coolant
He distinguishes between brain-derived melatonin that regulates sleep and melatonin produced inside mitochondria, which acts as a potent antioxidant and “coolant” against oxidative stress.
According to the proposed model, infrared light stimulates mitochondrial melatonin production and other protective mechanisms that keep mitochondria efficient and less inflamed.
Russell Reiter’s 2016 Journal of Pineal Research paper revealed that mitochondria produce their own melatonin at concentrations far higher than blood levels, neutralizing oxidative stress. Infrared exposure can increase this local melatonin production by 5-10 fold.
12. ACE2, COVID-19 and engine-temperature analogy
Dr. Seheult notes that ACE2 — the receptor used by SARS-CoV-2 — normally helps limit oxidative stress and protect tissues, functioning as part of the cooling system.
When the virus disables ACE2 across the body, everyone’s “engine temperature” rises, but people whose engines are already running hot due to chronic disease are the ones who fail on the metaphorical hill of COVID infection.
13. Vitamin D levels, mortality and supplement limits
Observational data during the pandemic consistently showed that higher vitamin D levels correlated with lower mortality and severity, prompting widespread supplementation.
However, he reports that high-dose supplements did not dramatically change outcomes in hospitalised patients, suggesting that vitamin D levels may be a marker for sunlight exposure and overall lifestyle rather than the primary causal factor.
A 2020 JAMA Network Open meta-analysis reported that vitamin D deficient patients had 2.6 times higher COVID-19 severity. However, a 2021 NEJM randomized controlled trial showed high-dose vitamin D supplementation did not significantly reduce mortality in hospitalized patients, suggesting vitamin D may be a marker rather than primary cause.
14. Seasons, latitude and pragmatic supplementation
In winter and at high latitudes, sunlight reaches Earth at an angle that filters out much of the UVB needed for vitamin D synthesis, making deficiency common and supplementation advisable.
Yet infrared light still penetrates, so he recommends maintaining outdoor light exposure year-round while using supplements to correct vitamin D deficits.
“In Seoul winter (37°N latitude), UVB barely reaches from November to February, making vitamin D synthesis impossible. During this period, 2,000-4,000 IU daily vitamin D₃ supplementation is recommended, while maintaining daytime outdoor activity for infrared benefits.”
15. Red-light devices and photobiomodulation
The conversation explores red-light masks and panels, referencing Glenn Jeffrey’s work showing that 670-nm light can improve mitochondrial function in the retina, skin and systemically in randomised trials.
Interestingly, benefits appear after roughly 15-20 minutes of exposure, after which additional light confers little extra effect, illustrating how photobiomodulation is dose-sensitive rather than “more is always better.”
UCL’s Glenn Jeffrey team reported in 2020 Journals of Gerontology that adults over 40 exposed to 670nm red light for 3 minutes each morning for 2 weeks showed 17% improvement in retinal function and 20% enhancement in color contrast sensitivity. Increased mitochondrial complex IV activity was the main mechanism.
16. Circadian rhythm, morning light and night-time screens
Dr. Seheult explains that even a couple of minutes of bright morning light can boost dopamine and set the brain’s clock for better mood, focus and sleep later that night.
In contrast, bright screens and LEDs in the evening suppress melatonin and disrupt circadian rhythms, raising long-term risks for dementia, depression, obesity and metabolic disease.
Stanford’s Andrew Huberman research team found that 10,000+ lux natural light exposure within 1 hour of sunrise resets the suprachiasmatic nucleus (SCN), advances cortisol peak by 90 minutes, and precisely initiates melatonin secretion 14 hours later. Evening blue light suppresses melatonin by over 50%.
17. Caffeine, melatonin supplements and dopamine
He discusses how caffeine blocks adenosine and can fragment deep sleep if taken too late, effectively “frying” dopamine circuits when misused, even if people feel subjectively alert.
Melatonin supplements can be helpful in specific situations but should not replace good light hygiene; long-term high-dose use may blunt the body’s own melatonin rhythms.
“Caffeine has a half-life of 5-6 hours. Coffee consumed at 2 PM remains in your system until midnight, disrupting deep sleep. Ideally, limit caffeine to mornings only and keep daily total under 400mg (4 cups).”
18. Dementia, cancer and a systems view of health
The episode connects genetic, nutritional and lifestyle data showing that low vitamin D and poor light-sleep patterns can raise dementia risk by 40-50% while appropriate supplementation and routine changes can substantially lower it.
Overall, viewers are encouraged to see sunlight, movement, sleep, environment and meaning as tightly interconnected levers for brain health and longevity, rather than treating vitamin D as a simple pill-based solution.
Lancet Commission 2020 report identified 12 lifestyle factors (education, hearing, trauma, hypertension, alcohol, obesity, smoking, depression, social isolation, physical inactivity, diabetes, air pollution) explaining 40% of dementia risk. Adding sunlight exposure and sleep quality raises preventable fraction to 50%.
Practical Health Q&A
5 Key Action Steps
- Morning sunlight 2 minutes: Outdoor natural light exposure within 1 hour of sunrise to reset circadian rhythm
- Noon outdoor activity 30 minutes: Vitamin D synthesis + infrared mitochondrial stimulation
- Pre-bedtime light control: Reduce brightness 50% after 8 PM, minimize screen time
- Sleep 7-9 hours secured: Consider polysomnography if sleep apnoea suspected
- Winter vitamin D supplementation: Target blood level 30-50 ng/mL
Conclusion—The Sunlight–Mitochondria–Dementia Connection
Dr. Roger Seheult’s interview transcends the vitamin D supplement debate, revealing how sunlight‘s entire spectrum (UVB + visible light + infrared) coordinates whole-body health through skin, eyes, mitochondria, circadian rhythms and melatonin systems.
The miraculous recovery of a 15-year-old boy, mitochondrial perspective on COVID-19 severity, window bed recovery speed differences, and infrared-local melatonin relationship combine clinical experience with cutting-edge research to clearly show long-term risks modern indoor, screen-centered lifestyles pose to brain health.
NEWSTART‘s eight pillars—nutrition, exercise, water, sunlight, temperance, air, rest, trust—are not merely health tips but an integrated system operating through common physiological mechanisms: mitochondria, oxidative stress, inflammation, circadian rhythms.
To prevent dementia, cancer, cardiovascular disease and extend healthspan, the key is redesigning light, time, environment and meaning rather than relying on pills—presenting a new paradigm for 21st century preventive medicine.