Did you know that vitamin D, also known as the “sunshine vitamin,” plays a big role in your night, too? If your vitamin D levels are on the lower end, it could actually be affecting your sleep. Worry not, though! Below, we’ll go over the evidence behind the effect vitamin D has on sleep and give you some suggestions for your best night of rest yet.
The science of vitamin D and sleepSeveral studies have shown an association between vitamin D levels and different measures of sleep. Low blood levels of vitamin D are associated with decreased sleep time, decreased sleep efficiency, and increased daytime sleepiness [1,2,3,4] To understand these terms, let's go over some definitions:
- Sleep time is simply the amount of time that you sleep
- Sleep efficiency is a measure of sleep based on the time it takes you to fall asleep and how many times you wake throughout the night
- Daytime sleepiness is a subjective measure of how sleepy/tired a person felt throughout the day
In short, these studies concluded that if your vitamin D is low you might sleep less, and even when you do sleep, it may be less efficient, less restful sleep. Translation? You’ll be sleepy the next day.
Furthermore, another study showed that improving vitamin D levels by taking a supplement improved sleep. This is important because it's one thing to say that low vitamin D is associated with undesirable sleep measures, but another to show that increasing vitamin D actually improves sleep. A randomized, controlled trial is needed to show a direct relationship between vitamin D and sleep. In this randomized, controlled trial study by Huang et al., patients were given supplements based on their vitamin D status. Overall, their vitamin D status improved from a mean of 18.57 ng/mL up to 26 ng/mL post-intervention, and their sleep time increased by about 45 minutes.
Several studies even saw a dose-dependent relationship between vitamin D levels and sleep.[1,2] This adds to the evidence that there is a direct, linear relationship between vitamin D and sleep measures. This also means that improving your vitamin D by any amount will improve your sleep. While reaching your optimal zone will result in the best sleep, just improving your vitamin D even just a little bit could improve your sleep by the same amount.
How it worksWithout getting too technical, researchers have found that there are vitamin D receptors on certain brain areas that control sleep. They hypothesize that your level of vitamin D affects sleep by binding to these receptors.5,6 If you have lower levels of vitamin D, theoretically you would have less vitamin D binding in the brain, and these brain areas may work a little differently than if you had a lot of vitamin D bound.
Vitamin D optimal zones
The InsideTracker vitamin D optimal zone ranges from 40 to 100 ng/mL. As long as your vitamin D level falls between these numbers, your sleep is as optimized as it can be in regards to vitamin D! An important note, though, is that a lot of other factors also affect sleep. Here, we are focusing on vitamin D specifically, but good sleep is a combination of a lot of things both internal and external to your body/biomarkers, and we would never claim that optimizing your vitamin D level is going to fix all of your sleep problems overnight. However, if your vitamin D is below optimal and you want to improve your sleep, increasing vitamin D could be a great first step.
Sources of vitamin DThe strongest source of vitamin D comes from the sun. When the sun hits your skin, the UVB rays react with a molecule in your skin and synthesize vitamin D. These reactions can be inconsistent, though, and factors like skin pigmentation, use of sunscreen, and the strength of the sun all affect the amount of vitamin D that you make.
If it is difficult for you to get vitamin D from the sun, you can also get it from food. Dietary sources of vitamin D include:
- Fatty fish such as salmon, tuna, and mackerel
- Fortified dairy and dairy alternatives
You can find many more options for food sources of vitamin D using InsideTracker’s nutrition page.
Vitamin D supplements are another great option that can give you that extra boost. In fact, vitamin D supplements are the most commonly used supplements among our InsideTracker users. Check out a recent blog we wrote on how to safely choose a supplement.
Because vitamin D plays a large role in the body, but can be difficult to get, testing your vitamin D level is very important! Testing takes the guesswork out of your health so you can take control and see exactly how your dietary changes affect your biomarkers. Test your vitamin D with us and receive a personalized set of recommendations for how to optimize your levels.
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- Tired of Being Tired: How I Optimized My Iron Levels
- Getting Back on Track: Laura Ingalls' InsideTracker-Fueled Journey Back to Holistic Health
- Avoiding The Crash: How Monitoring Iron Levels Can Save Your Season
- Stress Fractures: The Relationship Between Biochemistry, Nutritional Screening and Biomechanics
-  Beydoun MA, Gamaldo AA, Canas JA, Beydoun HA, Shah MT, McNeely JM, Zonderman AB. “Serum nutritional biomarkers and their associations with sleep among US adults in recent national surveys.” PLoS One. 9.8(2014).
-  Massa J, Stone KL, Wei EK, Harrison SL, Barrett-Connor E, Lane NE, Paudel M, Redline S, Ancoli-Israel S, Orwoll E, Schernhammer E. “Vitamin D and actigraphic sleep outcomes in older community-dwelling men: the MrOS sleep study.” Sleep. 38.2(2015): 251-257.
-  Hansen AL, Dahl L, Olson G, Thornton D, Graff IE, Froyland L, Thayer JF, Pallesen S. “Fish consumption, sleep, daily functioning, and heart rate variability.” J Clin Sleep Med. 15.10(2014): 567-575).
-  Huang W, Shah S, Long Q, Crankshaw AK, Tangpricha V. “Improvement of pain, sleep, and quality of life in chronic pain patients with vitamin D supplementation.” Clin J Pain. 29.4(2013): 341-347.
-  Musiol IM, Stumpf WE, Bidmon HJ, Heiss C, Mayerhofer A, Bartke A. “Vitamin D nuclear binding to neurons of the septal, substriatal, and amygdaloid area in the Siberian hamster (Phodopus sungorus) brain.” Neuroscience. 48.4(1992): 841-848.
-  Gominak SC, Stumpf WE. “The world epidemic of sleep disorders is linked to vitamin D deficiency.” Med Hypotheses. 79.2(2012): 132-135.