There seems to be no end to supplements that support sleep, but is vitamin D one? Research suggests vitamin D may be an important nutrient to improve sleep quality, duration, and latency.

While vitamin D plays an essential role in all sorts of functions—we’re talking about immune health, muscle growth, inflammation, bone health, and more—research has also found a strong link between vitamin D levels and sleep quality.

However, vitamin D is one nutrient that plays both sides where sleep is concerned—too little and you may experience sleep disruptions and poor-quality sleep, but taking it too close to bedtime increases the risk of experiencing the same thing. It’s all about finding that middle ground.

With that said, we’re diving into the details about the link between vitamin D and sleep.

Let's get into this!

What You Need To Know About The Sunshine Vitamin

While the human body can’t synthesize an abundance of nutrients, there are a few exceptions to the rule. Like plants undergo photosynthesis to provide their food, humans undergo a similar process in the formation of vitamin D.

When sunlight hits the skin, it sets in motion a cascade of biochemical reactions that form what’s known as ‘the sunshine vitamin.’

Although commonly referred to as a vitamin, vitamin D is actually a fat-soluble pro-hormone that has significant roles in maintaining health and well-being. It regulates the expression of hundreds of genes and is involved in everything from immune function and bone health, to mood, metabolism, and more.

Low vitamin D status can carry hefty health consequences and can exacerbate several conditions, including depression, IBS, metabolic syndrome, autoimmunity, and, yes, even sleep disorders 1-4.

Shining Some Light On Vitamin D Deficiency

Thanks to dermatologists and health professionals, it’s been drilled into us that sunshine is bad—but it’s not. We slather on sunscreen to protect the skin; we layer up with UV-protective clothing, and we shade ourselves from the rays that we so desperately need.

However, it’s easy to forget that the body requires adequate sunshine for the UVB rays that synthesize vitamin D, and without it, we run a major risk of deficiency.

Vitamin D deficiency is one of the most prevalent nutrient deficiencies, so much so that it has been titled a global pandemic; more than 40% of people are low in vitamin D, with the most affected group being African Americans 5.

But why is vitamin D deficiency such a big deal?

There’s growing evidence to suggest that vitamin D deficiency is associated with several chronic health conditions, some of which include 6:

  • Type I diabetes
  • Rheumatoid arthritis (and other autoimmune conditions)
  • Hypertension
  • Cardiovascular disease
  • Cancer

On top of that, vitamin D deficiency also results in poor mineralization of the collagen matrix in growing bone, which can lead to growth retardation and bone deformities in children.

In adults, deficiency can cause secondary hyperparathyroidism, which results in a loss of bone matrix and minerals, and increases the risk of osteoporosis, osteomalacia, and fractures 6.

If that wasn’t enough, low levels of pitman D could also cause muscle weakness, which subsequently increases the risk of falls and fractures.

There generally isn’t a single symptom that screams vitamin D deficiency, but one of the ways it typically manifests is through sleep disruptions.

Can Vitamin D Help You Sleep?

Most people don’t stop to think about how they’re sleeping. Maybe they’re sleeping for the recommended 7-9 hours, but how well are they sleeping? When it comes to shut-eye, it’s more about quality than quantity.

There’s been a fair bit of research suggesting that low vitamin D levels can contribute to sleep disturbances and/or exacerbate existing sleep conditions like insomnia.

One study reported that low vitamin D was associated with poorer sleep quality, while another suggests that dietary intake of vitamin D is linked to the midpoint of sleep, sleep duration, and maintaining sleep 7-9.

Other studies show similar results with increasing vitamin D intakes, leading to improved sleep quality, reduced sleep latency, increased sleep duration, and improved subjective sleep quality 10, 11.

But how does vitamin D play such a significant role in sleep?

The mechanisms behind the role of vitamin D in sleep aren’t completely clear, but research suggests that vitamin D receptors and the enzymes that control their activation and degradation are expressed in various regions of the brain that regulate sleep 12.

Vitamin D is also involved in the pathway that synthesizes the hormone melatonin, which regulates human circadian rhythms and sleep.

Vitamin D’s role in melatonin secretion, in part, has something to do with its actions on the expression of tryptophan hydroxylases (TPH)-2, which serves as the rate-limiting enzyme in serotonin—and consequently melatonin—production 13.

Vitamin D supports the expression of TPH to stimulate the production of serotonin in the brain 14, 15. Without adequate serotonin, melanin levels do not increase in the evening, which means that the body isn’t receiving the signals to sleep.

However, while vitamin D may play a role in synthesizing melatonin, can you take vitamin D at night? Many people may be under the impression that it functions like magnesium or tryptophan to support sleep, but that’s not the case.

Some research suggests that vitamin D at night can actually impair melatonin production, thereby interfering with sleep 16.

Final Thoughts

With all of that said, there’s a fair bit of research linking vitamin D levels with sleep quality and quantity.

Insufficient serum concentrations of vitamin D have been associated with poorer sleep quality, increased sleep latency, and decreased sleep duration. So, if you want to ensure you’re sleeping well, make sure your vitamin D stores are topped up.


  1. A Bahrami, SR Mazloum, S Maghsoudi, et al. High Dose Vitamin D Supplementation Is Associated With a Reduction in Depression Score Among Adolescent Girls: A Nine-Week Follow-Up Study. J Diet Suppl. 2018;15(2):173-182.
  2. EB Schmitt, J Nahas-Neto, F Bueloni-Dias, PF Poloni, CL Orsatti, EA Petri Nahas. Vitamin D deficiency is associated with metabolic syndrome in postmenopausal women.  2018;107:97-102.
  3. JC Branco, MF Cardoso, V Anapaz, et al. Vitamin D Deficiency in a Portuguese Cohort of Patients with Inflammatory Bowel Disease: Prevalence and Relation to Disease Activity. GE Port J Gastroenterol. 2019;26(3):155-162.
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