Medically reviewed by Patricia Mikula, PharmD
Taking vitamin D midday rather than before bed may help support sleep.
Credit: Pranithan Chorruangsak / Getty Images
Vitamin D may affect how much melatonin your body makes, which can affect how well you sleep.
Your body absorbs vitamin D better when you take it with a fatty meal.
For most people, it is safe to take vitamin D at any time of day.
Vitamin D is essential for overall health, including inflammation regulation, bone protection, and regular sleep patterns. Taking vitamin D supplements can help raise low levels. However, the time of day you take the supplement may affect its sleep benefits.
Can Vitamin D Disrupt Your Sleep?
Some research suggests taking vitamin D at night may interfere with how your body makes melatonin. Melatonin is a hormone your brain makes in response to darkness. It helps your body recognize when it is time to go to sleep, supporting your body’s natural sleep-wake cycle.
Sun exposure is the primary natural source of vitamin D. As a result, some research suggests your vitamin D levels should be highest during the day and lowest at night to support the sleep-wake cycle. In this case, taking a supplement midday rather than at night would be more beneficial.
Also, vitamin D can influence levels of serotonin, a hormone that affects mood and melatonin production. Normal vitamin D levels support the creation of serotonin, but studies have found that very high vitamin D levels from excessive supplementation may lead to low serotonin. Lower serotonin levels could lead to lower melatonin levels.
For example, a 2013 study in people with multiple sclerosis (MS) found that daily high doses of vitamin D led to low nighttime melatonin levels after three months.
Or Does Vitamin D Actually Help You Sleep?
Despite vitamin D’s potential to disrupt sleep, there is also evidence that it can improve sleep quality.
Low vitamin D levels are associated with a higher risk of sleep disorders, poor sleep quality, and less time asleep. Vitamin D levels higher than 20 nanograms per milliliter (ng/mL) or 50 nanomoles per liter (nmol/L) are usually considered adequate for bone and overall health.
In a 2022 research review, people with levels lower than 20 ng/mL were more likely to have unhealthy sleep habits.
The reason low vitamin D levels may affect sleep is not well understood. However, it has been seen in many groups of people, including people who are pregnant, people who work in factories, and people receiving hemodialysis (kidney failure treatment).
Vitamin D also indirectly regulates melatonin production. Low vitamin D levels may lower how much melatonin your body creates. However, as mentioned above, too high vitamin D levels could also lower melatonin production.
Low vitamin D may also lead to more inflammation in your body, which can disrupt sleep.
Overall, making sure your vitamin D level is not too low or too high will lower your risk for disturbed sleep.
Take Vitamin D With Fatty Foods
Vitamin D is a fat-soluble vitamin, which means it dissolves best in fats and oils. For optimal absorption, take the supplement with a fat-containing meal. Breakfast can be a good time to take the supplement. Examples of “healthy” fats include certain types of dairy, avocado, vegetable oils, nuts, and seeds.
In general, the type of fat you take with vitamin D doesn’t affect absorption. One study found no difference in absorption when vitamin D supplements were taken with different types of monounsaturated (MUFA) and polyunsaturated (PUFA) fats. Good sources of MUFA include nuts and seeds, avocados, olives, and olive oil. PUFAs are omega-6 and omega-3 fatty acids, like oily fish and seed oils.
If you take vitamin D without fatty food, your body will still absorb its nutrients. Taking it with fats just helps your body absorb the vitamin more effectively.
Certain foods also offer natural sources of vitamin D, including fatty fish, egg yolks, and certain cheeses. Eating these foods regularly can help support healthy vitamin D levels.
Consistency Is Key
Research on the best time to take vitamin D is mixed. The most important part about taking vitamin D is taking the supplement consistently. Ensuring that your vitamin D level is higher than 20 ng/mL (50 nmol/L) lowers your risk of illness.
If you have trouble remembering to take medications and supplements consistently, consider the following tips:
Take all medications at the same time of the day. Building this routine will help you remember to complete the task daily. Make sure to talk to your doctor first about potential interactions between vitamin D and your other supplements or medications.
Link taking your medications to another task you complete every day, like brushing your teeth or making breakfast.
Use organizer tools, like a pillbox or blister packs, to have all your doses in one place.
Use apps, alarms, electric pill bottles, or other reminders to alert you when it is time to take your medication.
Place your mediation in a convenient place for you to see it, like a counter or nightstand. Be sure to keep medications out of reach of pets or children.
Talk with a healthcare provider for more ideas on how to take your medication consistently.
When Is the Best Time to Take Vitamin D?
Overall, it is okay to take a vitamin D supplement at any time of day. If you notice you have trouble sleeping when you take the supplement later at night, take it earlier instead. However, if you forget to take your dose during the day, it is completely safe to take it at night. Taking the supplement with a fatty meal helps your body absorb it better, and taking the supplement consistently is key.
Talk with a healthcare provider to decide when taking a vitamin D supplement may work best for you.
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