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Does a Vitamin D Deficiency Cause Insomnia?

by Dale Cudmore | Updated: Jun 25, 2021

It’s easy to get a vitamin D deficiency, especially in winter months when you can’t get much sun.

There are some estimates that over 1 billion people worldwide have some degree of vitamin D deficiency (1).

It’s one of the most important vitamins for good health too. A deficiency can lead to a huge variety of conditions ranging from respiratory, to neurological, to heart diseases.

With so many potential side effects, it’s not surprising that researchers are still discovering ways that a vitamin D deficiency can affect health.

While insomnia isn’t noted as one of the most common side effects, both obstructive sleep apnea and depression are highly linked with insomnia (2). 

Those are 2 examples of how a deficiency might lead to sleep issues, but there is still much to uncover.

How Common is Insomnia With a Vitamin D Deficiency?

There’s a moderate amount of research that has looked at the effects of low vitamin D levels on sleep.

One study of older men found that subjects with low vitamin D blood levels had approximately twice the odds of having short sleep (under 5 hours) duration (3). They were also 1.45 times as likely to have a sleep efficiency (percent of time in bed spent asleep) under 70%.

An analysis of the 2005-2006 US NHANES found that low vitamin D levels were correlated with a longer time to fall asleep (4). There’s only so much you can draw from a survey, but it shows that a deficiency may affect all parts of sleep.

Finally, and most importantly, a 2018 meta-analysis found:

Vitamin D disorder also was associated with poor sleep quality, short sleep duration, and sleepiness.

Which also supports the above findings.

SummaryWhile there’s not a conclusive link between vitamin D deficiency and insomnia, there does appear to be a consistent link between a deficiency and increased risk of poor sleep quality. In certain situations, this could develop into long term sleep issues like chronic insomnia.

How Does a Lack of Vitamin D Cause Sleep Issues?

The effects of a vitamin D deficiency typically show after long periods of time, which make it difficult to study. Not to mention, side effects can include so many different things, which can be hard to monitor.

So it shouldn’t be too shocking that we don’t really know the specifics of why vitamin D deficiencies can cause sleep issues.

Additionally, vitamin D effects are based on many factors like age or race. One study found that black patients with vitamin D deficiency were more likely to experience excessive daytime sleepiness compared to white patients (5). Researchers can speculate why, but much further research is required.

SummaryThe exact mechanism(s) of how vitamin D affects sleep isn't very well understood currently.

How Much Vitamin D Do You Need?

Even without understanding all the complex interactions of vitamin D, we know that there are certain healthy levels people should aim for.

A 2 year study that gave subjects with sleep problems vitamin D supplements found that (6):

Most patients had improvement in neurologic symptoms and sleep but only through maintaining a narrow range of 25(OH) vitamin D3 blood levels of 60-80 ng/ml

It turns out that having too much vitamin D can also cause insomnia.

There’s also evidence that vitamin D supplementation can cause a negative change in gut microbiota that can cause side effects like arthritic pain after a long time period (2 years). Researchers found that supplementing both vitamin D and B resolved this specific issue (7).

Three months of vitamin D plus B100 (100 mg of all B vitamins except 100 mcg of B12 and biotin and 400 mcg of folate) resulted in improved sleep, reduced pain and unexpected resolution of bowel symptoms.

This might help explain why vitamin B12 deficiency is linked to insomnia.

So while most studies have patients with a vitamin D deficiency consume about 1,000 IU per day, taking a supplement blindly could be counterproductive (8).

SummaryIf you suspect that you have a vitamin D deficiency, have your serum levels checked by a doctor. Taking a supplement without confirming a deficiency, or taking too much of a supplement regardless could be dangerous.

Summary: Vitamin D and Insomnia

We’ve seen that low levels of vitamin D can lead to poor sleep quality, which could turn into insomnia depending on the person.

With that being said, there are many causes of sleep issues, and vitamin D deficiency likely isn’t the most likely suspect for those with insomnia symptoms.

If someone suspects they have a deficiency, they should get their blood levels checked to see if they’re in the healthy range or not. This can also catch other unknown issues (i.e. calcium deficiency can cause insomnia).

Supplementation can be a way to treat low vitamin D levels, but it’s also fairly easy to overdo it and suffer serious side effects.


  1. Understanding vitamin D deficiency
  2. Comorbidity between sleep apnea and insomnia
  3. Vitamin D and actigraphic sleep outcomes in older community-dwelling men: the MrOS sleep study
  4. Low vitamin D levels in adults with longer time to fall asleep: US NHANES, 2005-2006
  5. Vitamin D, Race, and Excessive Daytime Sleepiness
  6. The world epidemic of sleep disorders is linked to vitamin D deficiency
  7. Vitamin D deficiency changes the intestinal microbiome reducing B vitamin production in the gut
  8. An Evaluation of the Vitamin D3 Content in Fish

Medical Disclaimer: The information on is not intended to be a substitute for physician or other qualified care. We simply aim to inform people struggling with sleep issues about the nature of their condition and/or prescribed treatment.

About the authorDale is the founder of Snooze University and a sleep researcher. I overcame my sleep issues and now I'd like to help you do the same by summarizing the latest sleep studies for you.