Daytime sleepiness can be a sign of vitamin D deficiency, research suggests.
People with low levels of vitamin D are likely to wake more during the night and to have less sleep overall.
Vitamin D levels are linked to both sleep quantity and quality.
From October to March many people in northern climes do not get enough vitamin D.
As many as 50 percent of the world’s population is thought to be deficient in vitamin D.
Most people need around 10 micrograms per day, which can also be obtained from supplements.
Other signs of vitamin D deficiency include low mood, muscle fatigue, difficulties with learning and memory, gut problems and headaches.
The vitamin is thought to play a role in regulating serotonin, a neurotransmitter important for mood.
Foods that are rich in vitamin D include oily fish and eggs, but most people get their vitamin D from the action of sunlight on the skin.
Vitamin D is critical to the functioning of the whole body.
Some of the main risk factors for having low vitamin D levels are:
- being female,
- poor dietary habits,
- being older,
- living in northerly areas,
- and less exposure to sunlight.
The study included 81 people who had sleep problems.
Vitamin D levels were found to be lowest in those with the most daytime sleepiness, the results revealed.
Dr David McCarty, the study’s first author, said:
“While we found a significant correlation between vitamin D and sleepiness, the relationship appears to be more complex than we had originally thought.
It’s important to now do a follow-up study and look deeper into this correlation.”
The study was published in the Journal of Clinical Sleep Medicine (McCarthy et al., 2012).