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Vitamin D Plays Unexpected Role in Sleepiness in African Americans

Higher Vitamin D was found to correlate with excessive sleepiness, according to new research.

African American woman sleeping-- by Jenara Nerenberg

The Gist

Sleepiness affects us all at times, but scientists are now showing that there is a direct relationship with vitamin D—and for African Americans, higher vitamin D is correlated with more sleepiness, which is the opposite of the relationship found in other groups. The study in question, which appears in the December 15th issue of the Journal of Clinical Sleep Medicinewas conducted in Illinois and looked at sleep problems of 81 patients. The study raises new questions about the role of race, sleep, and vitamin D, as researchers have long asserted that more vitamin D means better sleep. The pigmentation found in different races may play a role in how the vitamin affects sleep, say the researchers.

The Expert Take

"What this study primarily does is start the conversation about another aspect of health and disease, namely the symptom of daytime sleepiness and other sleep disorders that may somehow be related to deficiency of Vitamin D," lead investigator Dr. David E. McCarty tells Healthline. "Many questions remain and much work needs to be done."

As a starting point, the findings from the study have implications for how physicians respond to complaints of sleepiness from African American patients. The question of how vitamin D affects sleep is now a concern.

"It will take further research to determine whether widespread screening for vitamin D deficiency in patients with sleep-related complaints is a valid recommendation or if supplementation of vitamin D deficiency provides incremental benefits in patients presenting with sleep-related complaints," says McCarty.

Source and Method

For this study, 81 sleep clinic patients participated in a consecutive series of examinations. All of these patients complained of nonspecific pain and sleep problems, and most of them were later diagnosed with obstructive sleep anea. Vitamin D levels were assessed using blood samples, and sleepiness was gauged using the Epworth Sleepiness Scale. 

The Takeaway

If you feel excessively sleepy, go see your doctor and ask about vitamin D, especially if you are African American. Sleepiness can stem from many causes and it is important to identify what is causing your daytime sleepiness. Likewise, physicians should remember to consider the role of vitamin D when presented with patients complaining of vitamin D, especially if they are African American.

"The way this study has changed my practice patterns comes from the realization that patients who present for complaints of possible sleep disorders are often vitamin D-deficient," says McCarty. "African Americans, in particular, are at high risk for vitamin D deficiency when these criteria are applied.

"Therefore, in the patients I see as a sleep medicine specialist, I tend to screen for vitamin D deficiency in patients who complain of nonspecific musculoskeletal pain, and I recommend supplementation for levels below 30 ng/mL."

Other Research

Research on vitamin D and excessive sleepiness is relatively new, but sleep research is not. A 2006 study shows that a two-hour mid-afternoon nap can reduce the sleepiness and raised cortisol levels that result from one night of poor sleep. An earlier study shows that abnormalities in the airway passages contribute to excessive sleepiness. Such abnormalities often go undetected and should not be neglected as the cause of sleepiness in teens and young adults, in particular. And, like many other studies on the topic, another study points out that excessive sleepiness should be taken seriously, because it raises the risk of traffic accidents.
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Tags: Latest Studies & Research

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About the Author

The Healthline Editorial team writes about the latest health news, policy, and research.