The Health Benefits of Sunlight

Metaphors about the effects of sunlight permeate our language. People are said to have a sunny (or cloudy) disposition, a bright outlook, or even a radiant or warm personality.

Although the prospect of fair weather is a source of positive feelings, there's also a sound physiological basis for the sun's association with an enhanced mood.

Sunlight Supports Vitamin D For a Healthy Mood

Vitamin D is known as "the sunshine vitamin" because, as most of us know, it is produced in the skin upon exposure to sunlight. Research shows it’s associated with a positive mood.

A study reported in the Journal of Nutrition found a 34% lower risk of depression in Japanese workers whose blood vitamin D levels were 30 mcg/L or more in comparison with those whose levels were less than 20 mcg/L.1

Another study conducted in Japan uncovered a relationship between higher vitamin D intake and a reduction in pregnancy-related depression.2 Additionally, the presence of post-partum depression three months following delivery has been associated with low vitamin D.3

Deficient vitamin D levels have been associated with depression in overweight women with polycystic ovarian syndrome.4 And in young men and women, low vitamin D levels were associated with depressive symptoms.5

Suicidal people have been found to have significantly lower mean vitamin D levels than non-suicidal, depressed individuals and healthy subjects.6

In recurrent cases of depression vitamin D levels were significantly reduced in comparison with healthy subjects.7

Vitamin D is not the only sunlight-derived factor associated with mood. Sunlight also stimulates the production of serotonin, a mood-boosting neurotransmitter.

Protect Yourself Against Excessive Sun Exposure

The dark side of sunlight is this: cumulative sun exposure significantly increases the risk of developing skin cancers. Although basal cell carcinoma, which is the most common type of skin cancer, is easily treated, melanoma can be far more serious, particularly if it is not detected early. 

Both of these skin cancers, along with squamous cell carcinoma, are related to the cumulative effects of ultraviolet light exposure.

This makes covering up when outdoors, particularly among those with light skin, a good idea, along with the liberal use of UVA and UVB-blocking sunscreen on exposed areas. 

So here's the catch—protecting oneself against sun exposure can result in deficient vitamin D levels, as is evidenced in cultures in which extensive covering of the body is the norm. And failing to receive enough light can result in fatigue and depression, particularly seasonal affective disorder. This is where supplements come to the rescue.

Take Vitamin D and Follow Up With a Blood Test

Vitamin supplementation is often required to maintain optimal vitamin D levels. Requesting a blood test (25(OH)D) is a smart way to determine if you’re getting enough.

Vitamin D deficiencies have been found even in those who spend time in the sun, so it's a good idea for everyone to undergo testing on an annual basis, along with their basic blood work.

The Bottom Line

If you’re outdoors for long periods of time, apply sunscreen. Have your vitamin D levels tested and supplement if necessary. Enjoy!


  1. J Nutr. 2015 Mar;145(3):541-6. 
  2. Nutrition. 2015 Jan;31(1):160-5. 
  3. BJOG. 2014 Sep 19. 
  4. Gynecol Endocrinol. 2014 Nov 4:1-4. 
  5. Nutrients. 2014 Oct 28;6(11):4720-30. 
  6. Psychoneuroendocrinology. 2014 Dec;50:210-9. 
  7. J Psychiatr Pract. 2014 Sep;20(5):329-37.


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