By Craig Weatherby
Sleep deprivation is at epidemic levels in the U.S. … and worldwide as well.
There's considerable evidence that lack of sleep promotes major health problems, including cardiovascular disease, depression, and obesity.
To the extent that seasonal affective disorder (SAD) disrupts sleep patterns, light therapy usually helps (Pail G et al. 2011) ... and vitamin D supplements may help, too (Stumpf WE et al. 1989; Gloth FM 3rd et al. 1999).
Lack of nighttime sleep leads to daytime drowsiness … and there's growing evidence that vitamin D deficiency can cause or worsen the situation.
Study links daytime sleepiness to low vitamin D levels
A clinical study linked, for the first time, daytime sleepiness to low levels of vitamin D (McCarty DE et al. 2012).
The credibility of the correlation was bolstered by the fact that daytime sleepiness was greatest in those with the lowest vitamin D levels … and vice versa.
A team from Louisiana State University Health Sciences Center recruited 81 people diagnosed with a sleep disorder – mostly obstructive sleep apnea – at the LSUHSC sleep clinic.
The volunteers' vitamin D blood levels were measured, and the extent of their daytime sleepiness was determined using a standard test (Epworth Sleepiness Scale).
The Louisiana State team found that in patients without vitamin D deficiency, sleepiness scores rose as vitamin D levels fell.
Among the patients who were vitamin D deficient (defined as lower than 20 ng/mL), sleepiness was directly correlated with vitamin D levels … but only in black people, not white.
The authors believe that this makes some sense because – compared with light skin – dark skin blocks more of the UV sunrays needed to produce vitamin D in the body.
(Frankly, that's an odd interpretation of the skin-color-based finding, since the correlation was not seen in white subjects who were equally vitamin D deficient, despite having light skin.)
The study could not determine whether vitamin D deficiency alone causes daytime drowsiness.
However, research from the authors and other teams suggests that low levels of vitamin D may promote daytime drowsiness … directly or by promoting or exacerbating chronic pain (Huang W et al. 2012).
It seems that daytime alertness can now join the many good reasons to ensure vitamin D adequacy.
You can best do that by eating fatty fish, taking supplements, and getting adequate (not excessive) exposure to UV sunrays.
Andersen ML, Tufik S. Vitamin D as an underlying factor in sleep-related issues. J Clin Sleep Med. 2012 Dec 15;8(6):699. doi: 10.5664/jcsm.2268.
Gloth FM 3rd, Alam W, Hollis B. Vitamin D vs broad spectrum phototherapy in the treatment of seasonal affective disorder. J Nutr Health Aging. 1999;3(1):5-7.
Gominak SC, Stumpf WE. The world epidemic of sleep disorders is linked to vitamin D deficiency. Med Hypotheses. 2012 Aug;79(2):132-5. doi: 10.1016/j.mehy.2012.03.031. Epub 2012 May 13.
Hoeck AD, Pall ML. Will vitamin D supplementation ameliorate diseases characterized by chronic inflammation and fatigue? Med Hypotheses. 2011;76(2):208-213.
Huang W, Shah S, Long Q, Crankshaw AK, Tangpricha V. Improvement of Pain, Sleep, and Quality of Life in Chronic Pain Patients With Vitamin D Supplementation. Clin J Pain. 2012 Jun 13. [Epub ahead of print]
Humble MB. Vitamin D, light and mental health. J Photochem Photobiol B. 2010 Nov 3;101(2):142-9. doi: 10.1016/j.jphotobiol.2010.08.003. Epub 2010 Aug 10. Review.
McCarty DE, Reddy A, Keigley Q, Kim PY, Marino AA. Vitamin d, race, and excessive daytime sleepiness. J Clin Sleep Med. 2012 Dec 15;8(6):693-7. doi: 10.5664/jcsm.2266. McCarty DE. Resolution of hypersomnia following identification and treatment of vitamin d deficiency. J Clin Sleep Med. 2010;6(6):605-608.
Pail G, Huf W, Pjrek E, Winkler D, Willeit M, Praschak-Rieder N, Kasper S. Bright-light therapy in the treatment of mood disorders. Neuropsychobiology. 2011;64(3):152-62. doi: 10.1159/000328950. Epub 2011 Jul 29. Review
Stumpf WE, Privette TH. Light, vitamin D and psychiatry. Role of 1,25 dihydroxyvitamin D3 (soltriol) in etiology and therapy of seasonal affective disorder and other mental processes. Psychopharmacology (Berl). 1989;97(3):285-94. Review.