December 16, 2012
Link Between Vitamin D, Race And Daytime Sleepiness Discovered
redOrbit Staff & Wire Reports - Your Universe Online
Individuals who find themselves getting sleepy during daytime hours may have vitamin D to blame, but the exact link between the two could depend upon their race, according to a new study.
Lead author David McCarty and colleagues discovered that in most patients, increasing levels of daytime sleepiness were inversely correlated with decreasing levels of vitamin D in their bodies.
However, the opposite was found to be true in African-American study participants, who felt higher levels of tiredness when their vitamin D levels were higher.
"While we found a significant correlation between vitamin D and sleepiness, the relationship appears to be more complex than we had originally thought," McCarty said in a statement on Friday. "It's important to now do a follow-up study and look deeper into this correlation."
In a paper published online in Saturday's edition of the Journal of Clinical Sleep Medicine, McCarty and colleagues Aronkumar Reddy, Paul Y. Kim, Andrew A. Marino, and Quinton Keigley, all from LSU, describe how they attempted to discover whether or not serum vitamin D levels were correlated with excessive daytime sleepiness, as well as to investigate whether or not a person's racial background or innate vitamin D deficiency played a role in the relationship between the two.
"The study“¦ involved a consecutive series of 81 sleep clinic patients who complained of sleep problems and nonspecific pain," the American Academy of Sleep Medicine, which publishes the Journal of Clinical Sleep Medicine, explained.
"All patients eventually were diagnosed with a sleep disorder, which in the majority of cases was obstructive sleep apnea. Vitamin D level was measured by blood sampling, and sleepiness was determined using the Epworth Sleepiness Scale," they added.
McCarty and his colleagues claim that this is the first study to demonstrate a "significant relationship" between sleepiness levels and vitamin D. They added that the racial factor makes sense because it has been established that higher levels of skin pigmentation is a risk factor for lower vitamin D levels.
While they did not intend for their work to establish a cause-and-effect relationship between the factors, they say that their research -- when combined with previous studies -- "suggests that suboptimal levels of vitamin D may cause or contribute to excessive daytime sleepiness, either directly or by means of chronic pain."