According to a paper published in the journal Dermato-Endocrinology, a large number of light-absorbing molecules (chromophores) found in the different layers of your skin absorb and interact with ultraviolet rays, producing a number of complex and synergistic effects.
For instance:
• Our body uses the near-infrared light spectrum to produce mitochondrial energy and maintain systemic equilibrium. Knowing this, it seems reasonable to conclude that if you're running low on adenosine triphosphate (ATP) — cellular energy — due to insufficient amounts of sunlight exposure, you'd start feeling sluggish and tired, and possibly depressed.
• Sunlight also regulates your circadian rhythm, and light therapy has been shown to be effective against both SAD and non-seasonal major depression. When it's dark, your melatonin levels increase, which is why you may feel tired when the sun starts to set. In the heart of winter, this may be at as early as 4 p.m.
• Ultraviolet (UV) light also stimulates epidermal cells known as keratinocytes to make beta-endorphins, which have a mood-boosting effect.
• Serotonin is also released in response to sunlight, which helps elevate your mood and energy.
• UVA generates nitric-oxide (NO) in your skin, which influences your body in a number of beneficial ways. It stimulates up to 60 percent of your blood to flow to your skin capillaries where the blood absorbs UV and infrared radiation, which can structure water in your body.
Additionally, the UVA actually helps kill any infections in your blood while the infrared recharges your cellular battery. NO also lowers inflammation, which could have a beneficial impact on your mental health seeing how depression is strongly linked to chronic, low-grade inflammation.
Reference:
Dermato-Endocrinology April/May/June 2012; 4(2): 109-117
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