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.
References:
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]
