Could our sleep problems have anything to do with a deficiency of vitamin D? A story about insomnia and vitamin D deficiency recently caught my eye, and a quick search of Pubmed turned up these article titles:
- “Low vitamin D levels in adults with longer time to fall asleep,” (International Journal of Cardiology, July 2013)
- “The world epidemic of sleep disorders is linked to vitamin D deficiency,” (Medical Hypotheses, August 2012)
- “Improvement of pain, sleep, and quality of life in chronic pain patients with vitamin D supplementation,” (Clinical Journal of Pain, April 2013).
None of these studies shows a definitive link between insomnia and low levels of vitamin D. Yet they do suggest that those of us with sleep problems might do well to examine our lifestyles and our diets to make sure we’re getting enough of the sunshine vitamin.
Vitamin D: How We Get It
Our bodies produce vitamin D with exposure to sunlight. We can also get it by taking vitamin D supplements (it is often combined with calcium) and by eating these foods:
- Fish and fish liver oils
- Fortified cereals
- Fortified soy products
- Salami, ham, sausages, and beef liver
- Fortified dairy products
- Egg yolks
Causes of Vitamin D Deficiency
You’re at higher risk for vitamin D deficiency if:
1) You get inadequate exposure to sunlight. This may occur because you’re homebound, have an indoor job, live in a northern latitude, or cover up or wear sunscreen all the time.
2) You’re vegan. Most natural sources of vitamin D are animal based.
3) You have dark skin. The pigment melanin cuts down on the skin’s ability to produce vitamin D when exposed to sunlight.
4) You are obese. People with a body mass index of 30 or higher often have low blood levels of vitamin D.
Recommended Daily Allowances
A simple blood test can determine definitively whether you’ve got a vitamin D deficiency, and if you suspect you do, pursue it with your doctor. But we can all make sure our daily intake of vitamin D falls within the Institute of Medicine’s current RDAs:
- 600 international units (IUs) for people aged 1 to 70
- 800 IUs for people older than 70
Back to the vitamin D supplement studies cited above: the subjects whose sleep improved took much higher dosages of vitamin D than the current RDAs. The safe upper limit for vitamin D is currently 4,000 IUs a day.