Sunlight exposure linked with improved brain function

I’m a huge advocate of sunlight exposure, on the basis that this mostly pleasurable endeavour is associated with wide-ranging benefits for the body. It also appears to benefit the brain. Lack of sunlight in the winter months can lead to lowering of mood and even depression that has been termed ‘seasonal affective disorder’. There is at least some evidence that SAD might have its root in vitamin D deficiency. Some research has found vitamin D therapy to help improve mood. See here for more details about this.

Vitamin D receptors (places where vitamin D can ‘connect’ and exert influence) are known to exist in the brain, including the cortex (outermost layer of the brain) and a structure known as the hippocampus. Both these brain regions have a role to play in brain function known as ‘cognition’ (which includes memory). This throws up the possibility that lack of sunlight might affect basic brain function in addition to mood.

In a recent study the association between season and sunlight exposure and cognitive function was assessed in a group of almost 17,000 American adults aged 45 or more [1]. In individuals with a history of depression, the researchers found that low levels of sunlight exposure were associated with a more than 2½ times increase in risk of impaired cognitive function. Now, an ‘epidemiological’ study of this nature does not provide that lack of sunlight and/or vitamin D impairs brain function in those prone to depression. However, it does at least support the notion that higher levels of sunlight and/or vitamin D are good for basic brain function. Remember, vitamin D receptors are found in parts of the brain involved in cognition ” this in itself is strongly suggestive that vitamin D exerts a modifying role here. And as it happens, a review on this subject found that some studies have found higher vitamin D levels to be associated with better cognitive function [2].

More research is needed to know for sure if upping sunlight exposure and/or vitamin D levels improves brain function. But right now, the role that sunlight and/or vitamin D play in basic brain function looks like a very promising avenue for researchers to pursue.


1. Kent ST, et al. Effect of sunlight exposure on cognitive function among depressed and non-depressed participants: a REGARDS cross-sectional study. Environ Health 2009 Jul 28;8:34.

2. Annweiler C, et al. Vitamin D and cognitive performance in adults: a systematic review. Eur J Neurol 2009 Jul 29 [Epub ahead of print]

4 Responses to Sunlight exposure linked with improved brain function

  1. Chris 24 August 2009 at 11:06 pm #

    Hi John, good post and indicative of a prominent role of vitamin D in mental function in addition to metabolic function.

    Perhaps there is more to the irritating expression ‘blue sky thinking’ than meets the eye .. or ear?

    I wonder sometimes if throwaway idiomatic expressions carry an almost embarrassing degree of validity that is easily overlooked in our information and techie age.

    ‘Blue sky thinking’ is one, and, though not related to health, ‘when the penny drops’ could be another. Again, apologies for indulgence on my part but when we really get to grips with issues of sustainability might ‘the green shoots of recovery’ take on new significance?

    It all leads back to the Sun.

  2. Harri 11 September 2009 at 12:27 am #

    Could you please advise where I can get a Vit D test? Also, I would like to start taking Vit D capsules but am having difficulty finding products of a level over 2000IU and want to ensure that the product I am taking is of a good quality – any pointers?

  3. Trinkwasser 14 September 2009 at 8:40 pm #

    do a mail order test and accept UK customers (I believe this is illegal in Canada)

    I use the Higher Nature 500iu caps which are tiny, you could easily take 4. Other high dose capsules are expensive. I know a doctor who recommends the liquid or emulsion.


  1. 3 health reasons you need to be out in the sun right now - Wellness Modalities - 10 April 2014

    […] like an obvious way to reduce stress, a screensaver for the brain. It’s much better than that. A study determined that “higher levels of sunlight and/or vitamin D are good for basic brain function.” […]

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