Can Vitamin D, B12, or Iron Deficiency Cause Insomnia and Harm Sleep?

Most Vitamins Have Little Impact, Iron Deficiency May Cause Restless Legs

Vitamin supplements may have little benefit on insomnia linked to deficiency
Vitamin supplements may have little benefit on insomnia linked to deficiency. Mario Tama / Getty Images

You may wonder, can vitamin deficiency cause insomnia? Just such a thing has been suggested by some in alternative medicine. It is said that one of the most common sleep ailments, insomnia, may occasionally be caused by a vitamin deficiency including vitamin D, B12, and iron. Can difficulty falling or staying asleep be linked to one of the vitamins that you may be lacking? Does taking vitamins help to improve sleep?

Discover the potential relationship with insomnia, restless legs syndrome, and sleep apnea and whether you might benefit from taking additional vitamin supplements.

How Might Vitamins Affect Sleep and Cause Insomnia

Though vitamin deficiencies may cause various neurological disorders, it is not a recognized cause of insomnia. In fact, research suggests that there is instead a correlation between those who take vitamins and insomnia. It is not clear if the vitamins worsen sleep, or if people who sleep poorly are seeking the aid of various vitamins.

Vitamin D deficiency is extremely common and it has been blamed for a wide variety of disorders. The skin is able to produce vitamin D with adequate sunlight exposure. It has even been implicated in poor sleep. The role in insomnia and sleep apnea is poorly defined. It is unlikely that vitamin replacement will help either disorder as the role is so doubtful.

Iron deficiency is commonly seen in those with restless legs syndrome. Uncomfortable feelings in the legs when lying down at night that are relieved by movement may make it hard to fall asleep. It can also be hard to get back to sleep after awakening in the night. Therefore, it may indirectly contribute to insomnia and improve with replacement.


There is no evidence that any other vitamin deficiencies undermine sleep. Importantly, vitamin replacement may have little or no impact on improving sleep, further suggesting the lack of importance with any weak association.

Alternative Treatments for Insomnia May Include Unproven Supplements

Some of these alternative medicine practitioners recommend various remedies for insomnia, including the consumption of vitamin-rich foods and even "a tablespoon of honey with milk." Although eating a balanced diet is important, and honey and milk may be comforting and tasty, it is unlikely that vitamin supplementation will cure a case of insomnia. In reviewing the medical literature, there is no scientific evidence supporting these claims.

There are other recommendations that may indeed help with insomnia, such as stress reduction, daily physical activity, and creating an environment that is conducive to sleep. These are part of the sleep hygiene guidelines, and may improve sleep as part of behavioral modification.

For those who suffer from chronic and persistent insomnia, evidence-based treatments such as cognitive behavioral therapy for insomnia (CBTI) are available and should be sought from reputable medical practitioners.

Bottom line: Unfortunately "vitamin-deficiency insomnia" is not a recognized disorder and the use of vitamin supplementation to cure insomnia is likely little more than a waste of vitamins.


Lichstein KL, et al. "Vitamins and Sleep: An Exploratory Study." Sleep Med. 2008 Jan;9(1):27-32.

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