Being in the sun has many benefits, including improved mood and cognition. (Louise McCoy/The Epoch Times)
Lack of sunlight in the winter months can lead to lowering of mood and even depression, that which has been termed seasonal affective disorder (SAD). There is some evidence that SAD might have its root in vitamin D deficiency. Some research has found vitamin D therapy helps improve mood.
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 the hippocampus. Both these brain regions play a role in 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 2.5 times increase in risk of impaired cognitive function.
Now, an epidemiological study of this nature does not prove that lack of sunlight 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 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 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 vitamin D levels improves brain function. But right now, the role that sunlight and 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. Environmental Health July 28, 2009, 8:34.
2. Annweiler C, et al. Vitamin D and cognitive performance in adults: a systematic review. European Journal of Neurology, July 29, 2009 [Epub ahead of print]
Dr. John Briffa is a London-based physician and health writer with an interest in nutrition and natural medicine. His Web site is drbriffa.com
