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The Connection Between Vitamin D and Sleep

Posted by Lauren Juarez on

The Connection Between Vitamin D and Sleep

What is Vitamin D? According to, Vitamin D is defined as, “A steroid vitamin which promotes the intestinal absorption and metabolism of calcium and phosphorus”. In layman's terms, Vitamin D helps your body to absorb calcium and promotes bone growth.

The body produces its own Vitamin D when exposed to sunlight, and it’s for this reason that it isn’t actually considered a vitamin (who knew?). Instead, it’s classified as a hormone – a fat-soluble one. Other than exposure to sunlight, you can also get Vitamin D through foods, like fatty fish and fish oils, egg yolks, and even foods such as dairy and juice, so long as they’re fortified. Don’t like those foods? Try supplements.

On the flip side, too little vitamin D can result in softer bones in children (known as rickets) and fragile, even misshapen bones, in adults (known as osteomalacia). Additionally, a deficiency in vitamin D has been linked to breast cancer, colon cancer, prostate cancer, heart disease, depression, and weight gain, as well as other conditions. Unfortunately, most people don’t maintain proper levels of Vitamin D – which can lead to some rather serious complications regarding your health. In fact, approximately 50% or more adults and children are deficient in Vitamin D, and is now recognized as a public health concern.

Vitamin D is essential to your body’s mental and physical health and may also be important for maintaining healthy sleep. Ironically, Vitamin D is inversely related to melatonin (otherwise known as the sleep hormone), so it's believed that nighttime is the best time to take it (preferably with a large meal). Research indicates that Vitamin D may influence both the quality and quantity of sleep and is associated with daytime sleepiness. A study done at Louisiana State University analyzed the relationship between Vitamin D and daytime sleepiness with two specific goals in mind. Primarily, they wanted to ascertain whether Vitamin D levels in the body contribute to excessive daytime sleepiness. Secondly, they wanted to assess the role ethnicity may play.

In an earlier study, researchers at LSU observed that more than half of the patients studied who had trouble sleeping along with experiencing chronic pain were also deficient in Vitamin D. They also noted that the symptoms were more prevalent in patients who were of African descent.

The primary – and most effective – way the body acquires Vitamin D is through exposure to sunlight. The exposure prompts our skin to manufacture Vitamin D. Increased skin pigmentation, however, can lower the rate of this happening - ergo, greater levels of skin pigmentation are considered a risk factor and can make you more susceptible to a deficiency.

The study completed by LSU included 81 patients, all of whom either had sleep issues or musculoskeletal pain either during the day or the evening, and sometimes both. Sixty-five percent of those studied were white, and thirty-five percent were African-American. All of the patients were diagnosed with a sleep disorder, with nearly three-quarters of the group having obstructive sleep apnea, and others suffered from either insomnia or restless leg syndrome (RLS). All subjects were assessed for excessive daytime sleepiness using the Epworth Sleep Scale, a standard measurement, and their levels of Vitamin D were measured using blood tests.

The results of the study found an distinct correlation between excessive daytime sleepiness and a Vitamin D deficiency. They also proved that race is a factor in the relationship between the two. The results, though, were surprising and indicated a rather convoluted relationship, especially where race is concerned.

The most important findings from the study are:

  • The subjects with greater skin pigmentation were found to have higher levels of daytime sleepiness and lower levels of Vitamin D, when compared to those with less skin pigmentation.
  • Just six percent of those studied without a Vitamin D deficiency were African-American.
  • Sixty-five percent of the subjects were found to have an inadequate amount of Vitamin D.
  • African-American patients made up thirty-five percent of those evaluated, and fifty-five percent of that thirty-five percent were deficient in Vitamin D.
  • Among those who were Vitamin D deficient – under 20mg as measured by a blood test – there was no connection between Vitamin D levels and daytime sleepiness. This is the opposite of what was expected when compared to earlier research.
  • An exception to the above was found among those of African descent who were Vitamin D deficient: There was a direct connection between the levels of Vitamin D and daytime sleepiness. Among these patients, higher levels of Vitamin D were associated with higher levels of daytime sleepiness – again, the opposite of what was expected.

Another study which included 3,048 men aged 68 and older measured sleep using wrist actigraphy, recording measurements of sleep time overall, wake time after the onset of sleep, and sleep efficiency – a measurement that resulted from comparing time spent in bed to the actual time spent sleeping. Among those studied, sixteen percent had insufficient levels of Vitamin D. To determine the influence of Vitamin D over sleep, the researchers considered several other factors, including: age, time (season) of year, additional health conditions, body-mass index (BMI), and both cognitive and physical functions. It was determined that low levels of Vitamin D were associated with several sleep issues:

  • Low levels of Vitamin D increased the chances that participants experienced inadequate sleep (less than 5 hours per night).
  • Low levels of Vitamin D were associated with lower sleep efficiency scores and a greater chance of scoring below seventy percent. (A healthy sleep efficiency score is typically considered to be eighty-five percent or higher.)

A lower sleep efficiency score is indicative of difficulties with the quality of sleep, as well as, potentially, the quality of sleep. A low score may also mean that it takes longer for you to fall asleep or may indicate that you’re an early riser. A low score can also mean that your sleep is fragmented and restless, with several awakenings throughout the night.

Other studies have demonstrated the correlation between low levels of Vitamin D and sleep issues. Though these studies have measured sleep subjectively, using survey data and reports from patients who have assessed their own sleep, in terms of quality and quantity.

Truthfully, there hasn’t been enough research on the relationship between Vitamin D and sleep. Though these studies may encourage further research and the potential influence on long-term health.

Again, there is no better source of Vitamin D than the sun - though there are numerous factors that can affect the amount of exposure you’re receiving, like the time of day or season, amount of cloud cover, and even air pollution. Of course, sunscreen and clothing can also obstruct your exposure of Vitamin D. Keep in mind that protecting your skin from overexposure is imperative, but some limited time in the sun without protection such as sunscreen may be good for your health, and your sleep. (The recommended amount for sun exposure to boost your Vitamin D intake typically falls between 5-10 minutes, from a few times a week to every day.)

Think you may be Vitamin D deficient? Here are some signs and symptoms to look for:

  • Feeling moody: The brain hormone, serotonin, increases with sun exposure. Studies show that low levels of Vitamin D in the body affect the amount of serotonin, AKA the “feel-good hormone”, in your brain causing you to feel moody and irritable.
  • Chronic pain: If you experience regular aches, muscle weakness and joint pains, you may be Vitamin D deficient.
  • Constant fatigue: You feel tired and lethargic often, despite being well rested, and may also feel anxious. An adequate amount of Vitamin D in the body is known to boost energy levels and increase muscular function.
  • Daytime sleepiness: Numerous studies show that people with low levels of Vitamin D are more inclined to experience daytime sleepiness and other sleep disorders.
  • Sweaty head: One of the most common indicators of a Vitamin D deficiency is head sweating.
  • Frequent flu sickness and/or respiratory infections: You may be more susceptible to allergies and infections. Vitamin D reduces inflammation and regulates your immune system.
  • Gum disease: Bleeding, reddening and swelling of the gums may also be indicative of a Vitamin D deficiency.

Still not sure if you’re getting enough Vitamin D? Have your doctor perform a blood test, or check out If you’re like countless other people and your Vitamin D levels are low, then you and he/she can come up with a plan that may include some dietary changes, controlled exposure to sun, and/or supplements, to bring your levels up and maintain them. Making the necessary changes to ensure your Vitamin D levels are healthy is good for your overall health and is also likely to be better for your sleep.

Thanks for reading!