<aside> <img src="/icons/flash_blue.svg" alt="/icons/flash_blue.svg" width="40px" /> Key Takeaways:
Rise with the sun and wind down as it sets, limiting exposure to artificial light in the evening hours
See direct sunlight for 5+ minutes at the earliest opportunity
Spend a minimum of 20 minutes per day in the sun, ditching the sunglasses and blue light blockers during this period
My personal preference is to spend longer than this if accessible, wearing a naturally derived sun block if I’m at risk of burning
Reduce evening light exposure:
<aside> <img src="/icons/fireworks_blue.svg" alt="/icons/fireworks_blue.svg" width="40px" /> Ancient Egyptians worshipped the Sun as a god, Ra. The creator of the universe and giver of life. A symbol of warmth and growth.
The Greeks thought the sun was Apollo's fiery chariot, travelling through the sky and giving light to the planet. They believed Apollo was the god of medicine and healing, but he could also bring sickness.
Nowadays, scientists know that sunlight has both positive and negative effects on human health.
Let's start with the negative effects:
Public health messages have mostly been about the dangers of too much sun.
UVA rays (95-97% of the UV rays that hit Earth) go deep into the skin and can cause skin cancer by creating DNA-damaging molecules like hydroxyl and oxygen radicals.
Sunburn is caused by too much UVB (ultraviolet B) radiation; this form also leads to direct DNA damage and promotes various skin cancers.
Both forms can damage collagen fibres, destroy vitamin A in skin, accelerate aging of the skin, and increase the risk of skin cancers.
Does this imply that we should avoid the sun?
No, because the sun has serious benefits to offer..
The best-known benefit of sunlight is its ability to boost the body’s vitamin D supply.
Vitamin D deficiency is often because of insufficient sun exposure.
Turns out, 1,25-dihydroxyvitamin D3, the active form of the vitamin, regulates a whopping 1,000 genes that impact various tissues, including calcium metabolism and immune system functioning.
What about the vitamin D production?
Unlike other essential vitamins, which humans must obtain from food, the skin can synthesise vitamin D through a photosynthetic reaction when exposed to UVB radiation.
When this photosynthesis happens, it creates vitamin D3. This gets transformed into 25-hydroxyvitamin D, which is the main form of vitamin D in your blood.
Doctors use this to check if you have enough vitamin D.
How efficiently we produce depends on how many UVB (ultraviolet B) photons get through, but clothing, excess body fat, sunscreen, and melanin can raise a barrier.
For most white individuals, half an hour in the sun in a bathing suit can trigger the release of 50,000 IU (1.25 mg) of vitamin D into the circulation within 24 hours of exposure.
This same amount of exposure yields 20,000–30,000 IU in tanned individuals and 8,000–10,000 IU in darker-skinned individuals.
Another set of transformations occurs in the kidney and other tissues, forming 1,25(OH)D.
This vitamin is like a hormone, similar to the steroid hormones.
1,25(OH)D builds up in cell nuclei of the intestine, helping to absorb calcium and phosphorus. It controls the movement of calcium in and out of bones to manage bone-calcium metabolism.
Vitamin D's primary job is to keep calcium and phosphorous levels in check so our bodies can function properly.
Without sufficient vitamin D, bones will not form properly. In children, this causes rickets, a disease characterised by growth retardation and various skeletal deformities, including the hallmark bowed legs.
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<aside> <img src="/icons/light-bulb_blue.svg" alt="/icons/light-bulb_blue.svg" width="40px" /> As diurnal creatures, we are programmed to be outdoors while the sun is shining and home in bed at night.
Direct sunlight in the morning boosts cortisol by up to 50%, the hormone released to wake you up—getting you fired up for the day.
On the flip-side, melatonin is produced during the darker hours. Even a short glimpse of light in the eye will interfere with this production.
When we are exposed to sunlight or very bright artificial light in the morning, our nocturnal melatonin production occurs sooner, and we enter sleep more easily at night.
The melatonin precursor, serotonin, is also affected by exposure to daylight. Normally produced during the day, serotonin is only converted to melatonin in darkness.
High serotonin levels are associated with short nights and long days (i.e., longer UVR exposure).
Serotonin promotes positive moods, improved cognition, higher sexual desire and libido, reduced anxiety, and more.
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