Article: Sun exposure: Benefits beyond D production
Here is what we know, sometimes incompletely, about the effects of sun exposure on the human body:
1. Enhances mood and energy.
Generally, a little bit of sun exposure is associated with better mood,
while tanners commonly report feeling more relaxed than non-tanners.
One study demonstrated that β-endorphins increase after sun exposure,
which would explain this association. Three studies found no increase in
β-endorphin production after sun exposure, but the authors speculate
that the anxiety from a blood draw to check on endorphins would
negatively affect endorphin levels.
2. Treats skin diseases.
These diseases include treatment of lupus vulgaris, psoriasis,
vitiligo, atopic dermatitis and localized scleroderma. Why phototherapy
works in the treatment of these diseases is not completely understood
(usually broadband UVB or narrow-band UVB, but sometimes UVA also),
researchers do know of some mechanisms during phototherapy. UV radiation
reduces the rate of cell proliferation in the skin, activation and
proliferation of melanocytes, reduction of T-lymphocytes, and reduction
of Langerhans and mast cells.
3. Relieves pain in fibromyalgia.
Sunbathing seems to have potential to reduce pain in patients with
fibromyalgia compared to no exposure. The mechanism is unknown.
4. Skin barrier functions. Skin exposed to UVB and UVA is more resistant to primary irritants. Once again, the mechanism is unknown.
5. Protects from disease beyond vitamin D?
In an animal model, researchers discovered that sun exposure is more
protective and suppressive against multiple sclerosis than just vitamin D
alone.
6. Induces nitric oxide.
UVA exposure induces nitric oxide (NO*) production. It
has been suggested that NO* protects the skin for 20-30 minutes from UV
damage, offers cardiovascular protection, helps wounds and have some
anti-tumor activity.
One area that the authors did not mention
was melatonin regulation. It is believed that the more light one is
exposed to during the day, the sooner melatonin production occurs at
night. Melatonin is involved in the sleep-wake schedule and when
released, makes the body drowsier and cooler.
While there is
much work to be done in the realm of figuring out specific mechanisms of
action induced by UV exposure, we have some clues as to what sun
exposure accomplishes outside of vitamin D production.
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