At BioAge UK, we believe that longevity isn’t something you buy in supplement form, it’s something you build, one habit at a time.
Nutrition, exercise, good sleep, stress management etc etc. But a very basic and yet often forgotten longevity factor is light. Or more precisely: light and darkness. 🌞🌚
I listened to a podcast recently with Dr. Roger Seheult, a critical care doctor who spends his life at the edge of survival. He told the story of a 15-year-old boy, battling aggressive blood cancer, who developed a rare, life-threatening fungal infection. He lost a lung. His condition deteriorated. The infection spread to his remaining lung and the doctors gave him 48 hours to live.
When asked what he wanted to do with his final days, he said something simple: “I want to go outside.”
So they wheeled him out into the sunlight. He laid there, breathing open air and feeling the warmth on his skin. They also began using a light therapy device.
What happened next seemed impossible: within 48 hours, his infection began to recede. His white blood cell count dropped. His need for oxygen decreased. By day five, he was improving rapidly. A CT scan showed 60–70% of the infection is gone. He survived.
Nothing else had changed. No new medications. Just light.
This isn’t an ‘old wives tale’. This is straight from the doctor who treated him and has gone on to replicate ‘light therapy’ for many more patients.
He has a vision for hospitals, where patients are wheeled out into sunlight, where light is part of the care plan and darkness is respected. Not just machines and medications but nature.
🔄 Circadian Rhythm: The Missing Piece of Longevity
We often talk about vitamin D in the UK, especially in winter but we rarely talk about what sunlight actually does. It’s not just about topping up your D levels.
Sunlight penetrates the body, down to the mitochondria, triggering the production of melatonin inside your cells. Not the sleepy kind you get in a supplement, the cellular kind that acts as a cooling antioxidant for your mitochondria. Without this cooling system, our cells overheat, burn out, and age prematurely.
Melatonin is your mitochondria’s fire extinguisher and it only works if you’re getting the right light at the right time of day and the darkness at night to match.
Sunlight is the start but circadian rhythm is the system.
Your body runs on a roughly 24-hour internal clock. Light cues in the morning wake you up, trigger cortisol, switch on metabolism, and energise you. But darkness at night triggers melatonin production, repairs your brain, balances hormones, and detoxes your cells.
When you miss these environmental signals or override them with artificial light, late screens, or disrupted sleep, everything from weight gain to inflammation to cognitive decline accelerates.
For midlife women, this becomes even more critical. Hormonal shifts make us more sensitive to light disruption, poor sleep and mitochondrial decline.
🌞🌚 How Light & Darkness Affect Ageing
When we think about health, we often focus on food, exercise, or supplements. But one of the most powerful regulators of your biology is something most of us don’t even realise we’re missing: natural light and darkness.
Your body runs on a 24-hour internal rhythm, the circadian rhythm, which governs everything from hormone production to brain detoxification. Morning sunlight helps set this rhythm: it boosts cortisol naturally, increases alertness, and triggers a cascade of daytime metabolic activity.
But just as important is what happens at night.
As the sun sets and darkness falls, your brain is meant to shift gears, switching from action mode to repair mode. Darkness triggers melatonin production, which doesn’t just make you sleepy. It also:
- Repairs damaged cells
- Supports mitochondrial function
- Lowers inflammation
- Enhances brain detoxification
- Balances mood and immune response
And here’s the crucial part: melatonin made at night isn’t the same as the kind your mitochondria produce in response to sunlight. One supports rest; the other supports energy. You need both. And both depend on respecting nature’s rhythms.
Yet many of us are out of sync:
- We wake up to a phone screen, not sunlight
- Spend our day indoors under fluorescent light
- Then expose ourselves to blue light at night, suppressing melatonin
- And wonder why we feel tired, wired, foggy, or inflamed
This misalignment doesn’t just make us feel off, it accelerates ageing at the cellular level.
If you’ve been struggling with sleep, energy crashes, low mood, hormonal imbalance, or stubborn weight, the issue might not just be what you’re eating or lack of movement, it could also be how your cells are reading the time of day.
🌿 Why This Matters for Midlife Women
✨ Final Thoughts
Our clients, mostly women in their 40s, 50s, and 60s, often come to us feeling tired, foggy, anxious, and not quite themselves. They’ve “tried everything,” (eating well, smart training, getting their steps in etc) and yet something still feels off.
Simple shifts can change everything:
- Stepping outside for 5 minutes first thing
- Regular walks outdoors and preferably surrounded by nature
- Blocking blue light in the evening
- Creating evening rituals with true darkness
- Generally spending more time in natural daylight (even in cloudy Britain!)
This isn’t b*llocks! I see a lot of fitness coaches who don’t understand midlife women, still insisting that the only things that matter are calorie deficit and exercise. Now that is b*llocks! This is root-cause, mitochondria-level medicine. This is longevity in action.
This isn’t about living forever. It’s about living healthier, with more energy and being able to do all the things you want, for longer.
So whether you’re navigating perimenopause, managing chronic fatigue, or just feeling out of sync, consider this your nudge to get outside. Wake with the sun. Wind down in darkness. Reclaim the rhythm your body has always known.