Many studies have been performed on the link between vitamin D and sleep. A notable one comes from Anthony Norman from the University of California at Riverside, who's a recognized authority on vitamin D research. In August 2008, Norman published a paper in the American Journal of Clinical Nutrition. In it he showed links between vitamin D and a strong immune system, healthy heart and strong mind. All of these things are also helped by better sleep achieved when the body gets an adequate supply of vitamin D.
Vitamin D is produced naturally in the body when exposed to sunlight. People who are in the sunlight during the day tend to sleep better at night. This is the result of a healthy supply of Vitamin D in the body. Those who do not get enough sunlight exposure can become vitamin D-deficient and experience sleep difficulties. Ten minutes of arm and leg skin exposure to the sun at midday is sufficient for a day's worth of Vitamin D production. The same results can be achieved by a 1/2 hour in the sun twice per week.
Vitamin D is also abundant in certain foods. These include oily fish such as salmon, cod and mackerel. Shrimp, milk and eggs are also excellent sources of vitamin D. Nutritional supplements can be taken to compensate for a vitamin D deficiency. However, it's always better to get your vitamin D from natural sources if possible. People with adequate amounts of vitamin D in their diets tend to sleep better.
The recommended daily allowance of vitamin D is 200 IU. "IU" stands for international units. Older people require more vitamin D. People between the ages of 50 and 70 should get at least 400 IU; those older than 70 should get at least 600 IU. These are minimum numbers. Dr. Norman urges adults to ingest at least 2,000 IUs of vitamin D per day in order to improve sleep.
It's dangerous to ingest too much vitamin D. Those who get more than 10,000 IU of it per day run the risk of getting hypercalcemia. This is a vitamin D overdose. It can result in constipation, kidney stones and bone pain. In extreme cases, it can cause coma and death. Getting too much vitamin D interferes with the ability to get good sleep. The key is to strike a balance and get a proper amount of vitamin D in your system.