When to Take Vitamin D and How It Affects Your Sleep

By: Dave Asprey
March 12, 2020

When to Take Vitamin D and How It Affects Your Sleep

  • Low vitamin D levels affect your entire body, including your sleep.
  • Researchers aren’t sure how vitamin D affects sleep (yet). What we do know is that raising vitamin D levels is associated with better sleep quality.
  • Keep reading to find out when to take vitamin D, plus tips to naturally increase your levels.

You might know that a large percentage of the U.S. population is low in vitamin D. What you may not know is that low vitamin D levels can lead to insomnia and other sleep disorders — yikes. Unless you have access to adequate sun exposure, taking a vitamin D supplement is an easy way to get your levels up. However, there are nuances to when to take vitamin D and how much to take. Here’s what you need to know.

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Vitamin D and sleep

Woman walking in sunshine

More than half of the world population is deficient in vitamin D.[1] That’s a problem because your body uses vitamin D for every system in your body, from maintaining bone health to supporting immunity. Low levels of vitamin D are directly related to the amount and quality of sleep you’re getting.

Rodent studies have found vitamin D receptors in the parts of the brain that regulate sleep.[2] [3] Clinical studies (in people) have found that low levels of vitamin D are associated with poor sleep quality. In one uncontrolled study, participants who brought up their vitamin D levels saw significant improvement in sleep and neurologic symptoms [4]

In another study,[5] researchers looked at the vitamin D levels and sleep quality of 3,048 men 68 years and older. They measured total sleep time, wake times and frequency and “sleep efficiency,” which measures the time spent in bed versus the time spent sleeping. The study found that low levels of vitamin D were related to poor quality sleep and sleeping less than 5 hours a night. Low levels were also associated with lower sleep efficiency scores.

We’re just beginning to understand how vitamin D plays a role in sleep. In a 2017 study of vitamin D and sleep quality in hemodialysis patients, researchers suggest that vitamin D may affect your shut-eye by interacting with the areas of the brain thought to regulate sleep. On the other hand, vitamin D plays a key role in supporting your immune system, and managing inflammation may support better sleep quality.

And the amount isn’t the only thing that matters: You should also pay attention to when you take vitamin D.

When to take vitamin D for sleep

Clock next to when to take vitamin D text
Early research suggests vitamin D is inversely related to melatonin, your sleep hormone.[6] This means that increasing vitamin D levels may suppress melatonin levels.[7] So, it makes sense that taking it at night could disrupt your sleep.

I’ve noticed this effect personally. When I’ve taken vitamin D in the morning I had my usual great sleep. When I’ve taken it before bed, I had a restless night. Part of being Bulletproof is paying attention to how small changes make you feel. If you take vitamin D before bed, pay attention to how refreshed you feel the next day.

The other benefit of taking vitamin D in the morning: this is a fat-soluble vitamin, which means it’s best absorbed when you take it with food. Have it with breakfast or a cup of Bulletproof Coffee when you take your other supplements. That’s one more thing to cross off your to-do list.

Related: How to Sleep Better: Science-Backed Sleep Hacks to Wake Up Ready to Go

Start hacking your sleep with vitamin D

Man sleeping

If you are unsure of where to start, get your baseline levels. Ask your doctor for updated vitamin D tests every six months or so. You can also test your levels at home using a self-testing service like WellnessFX.
The recommended daily amount of vitamin D is 600 IU (15 micrograms) for those between the ages of 1 to 70.[8] If your levels are low, learn how to get more vitamin D — plus other reasons to up your intake.

Find out how to get the best sleep ever with the Bulletproof Sleep Roadmap. Enter your email to download your free copy!

Want to Sleep Better? Get Your FREE Guide

Learn why you're not sleeping and find out how to wake up feeling refreshed. Enter your email to get your free guide!

This is an updated version of an article originally published Sept. 2012.