Sun exposure, good or bad? Part-2


Sun UV rays suppress weight gain and diabetes onset.

Dr.Shelley Gorman from the Telethon Kids Institute and her colleges studied the effect of sunlight, simulated by shining a UV light, had on mice that were overfed. These mice showed a decline in diabetes risk factors, including abnormal glucose levels and insulin resistance. The research team attributed the beneficial effects of the UV treatment for mice at risk of diabetes to nitric oxide.
They reached this conclusion by applying a cream that contained nitric oxide to the skin of the mice, while other mice received vitamin D supplementation. The cream triggered the same obesity and diabetes slowing effects as UV exposure, while vitamin D supplementation had no effects.
Dr. Richard Weller, senior lecturer in dermatology at the University of Edinburgh, says: ‘We know from epidemiology studies that sun-seekers live longer than those who spend their lives in the shade”, so studies like this one are helping us to understand how the sun can be good for us’ (10).


Sun exposure helps to lower blood pressure, cutting the risk of heart attack and stroke.

Nitric Oxide (NO) is a compound produced by the blood vessels lining or endothelium and it is a powerful vasodilator, it relaxes narrowed blood vessels, increasing oxygen and blood flow. NO is abundant in the upper skin layers and when exposed to the sunlight, it is transferred to the blood contributing to regulate blood pressure.


Sunlight improves cognitive function.

A large cohort study published on the Journal of Environmental Health found an association between decreased exposure to sunlight and increased probability of cognitive impairment (8).


Sun UV rays help to treat skin disorders

Some doctors recommend psoriasis patients suffering to sunbathe at least three times a week (12). Light therapy is also a common treatment for this condition.
Also, there is evidence that skin exposed to UVB and UVA is more resistant to several irritants than normal skin, which may indicate the improvement of skin barrier functions (13).


Being in the sun for 20 to 30 minutes improves mood and makes you feel good.

Sunlight boosts β-endorphin production. Dr. David Fisher a researcher in the Harvard Medical School in Boston made an experiment with rats to confirm the theory that sun exposure increases our β-endorphin levels. Dr. Fisher and his colleagues gave mice a daily dose of UV light for 6 weeks, which is equivalent to what a light-skinned person would receive while lounging in the midday Florida sun for 20 to 30 minutes. The team then measured levels of β-endorphin and found an elevation of endorphin levels ranging from 30% to 50% after mice got their daily hit of rays (9). Endorphins interact with the opiate receptors of the brain to reduce our perception of pain. Besides reducing our feelings of pain, secretion of endorphins leads to modulation of appetite, release of sex hormones, enhances our immune response, produces feelings of euphoria, and reduces the negative effects of stress (7).


Sun exposure helps to avoid the winter blues.

Sunlight leads to higher serotonin levels and it is a standard treatment for seasonal depression (12), however, some studies suggest that it could also help in the treatment for nonseasonal depression and to reduce depressed mood in pregnant women (11).






(1)Phenotypic markers, sunlight-related factors and sunscreen use in patients with cutaneous melanoma: an Austrian case-control study.
(10) Geldenhuys S, Hart P, Gorman S, et al. Ultraviolet Radiation Suppresses Obesity and Symptoms of Metabolic Syndrome Independently of Vitamin D in Mice Fed a High-Fat Diet. Diabetes. 2014.