ficiency, there was a direct correlation between levels of Vitamin D and daytime sleepiness. Among these patients, higher Vitamin D levels were associated with higher levels of daytime sleepiness-the exact opposite of what was expected.
It is this last finding that is unexpected, and surprised researchers themselves, who expected to see lower levels of Vitamin D associated with higher levels of daytime sleepiness.
Why might this have been the case? Additional research clearly is needed to further explore the role that skin pigmentation may play in Vitamin D deficiency and its effect on sleep, and daytime sleepiness in particular. This was a small study, and larger-scale research may provide a clearer picture of this complicated relationship.
There are other important questions that arise. We can see an association between Vitamin D deficiency and daytime sleepiness, but we don’t have an understanding of cause and effect. Is Vitamin D deficiency directly responsible for excessive daytime sleepiness and other sleep problems? Or is poor sleep a consequence of other medical conditions associated with Vitamin D deficiency, such as chronic pain? What are the biological mechanisms by which Vitamin D—and a lack thereof—affect sleep functions in the body? There’s a lot we don’t yet know about the relationship between Vitamin D and sleep.
If you’re at risk for Vitamin D deficiency, talk to your doctor. Supplements, dietary changes, and safe and controlled exposure to sun can all help boost levels in the body. Making sure your body has sufficient levels of Vitamin D offers important health protections and, perhaps, a welcome boost of energy in place of daytime sleepiness.
Michael J. Breus, PhD
The Sleep Doctor™