does taking vitamins late at night keep you awake?

7 Really Surprising Vitamins That Keep You Awake at Night

There are few things worse than not being able to sleep at night. If you’re not sleeping right, there are dozens of things that could be behind the problem.

Most people don’t realize that vitamin supplements can cause sleepless nights. Since vitamins are essential nutrients your body needs to function, it sounds counterintuitive.

However, vitamins A, B5, B6, B12, C, D, and K can keep you awake at night. They can also cause side effects like nausea, diarrhea, and muscle cramps.

It’s not the vitamins that are the problem. It’s when you exceed the recommended daily allowance (RDA). You also have to take vitamins early in the morning with food. Otherwise, taking vitamins can have unintended side effects.

Why Do Vitamins Keep You Awake?

In terms of anecdotal evidence, there’s no shortage of people who can give opinions on vitamins and sleep. However, there’s little information when it comes to hard scientific evidence. Only a few studies have been done on which vitamins keep you awake or why.

The most important study was published in the Journal of Sleep Medicine. It was a medium-scale experiment on hundreds of U.S. citizens that sought to determine whether taking a vitamin or mineral supplement affected sleep time or sleeping patterns.

They found that using a multivitamin or multiple single vitamins was associated with poor sleep maintenance compared to individuals who did not take vitamin supplements. Taking vitamins seems to make you sleep worse.

They suggested that it could be because:

  • Vitamin use causes poor sleep in certain individuals, i.e. genetics
  • Multiple vitamins combine to disturb sleep
  • People who take vitamins may have chosen to do so because they sleep poorly
  • People with depression or anxiety, which both cause poor sleep, may take vitamins to aid their conditions

They were unsure why people taking vitamins sleep worse. However, they may have overlooked the effects on serotonin and melatonin production.

These two chemicals dictate when we feel awake and when we feel sleepy. Several vitamins affect the production of these chemicals. However, there is no scientific consensus on the matter.

What Vitamins Cause Sleeplessness?

There are a surprising number of vitamins that cause insomnia. In fact, there are more that do than don’t. However, as mentioned, the trick is to take them correctly.

You have to ensure that you don’t go over your RDA and take them at the right time. This will normally solve your sleepless nights.

Let’s look at which vitamins can keep you awake at night:

what vitamins can cause insomnia?

1/ Vitamin A

Vitamin A can keep you awake at night if you take it at the wrong time. Vitamin A, or retinol, is one of the vitamins that sets the circadian rhythm.

The circadian rhythm is the 24-hour body clock that regulates, among other things, the time that we sleep. Vitamin A plays an important part in our body clock.

Specifically, vitamin A plays a significant role in eye health. It keeps the eyes healthy, and it is beneficial to our eyesight.

Vitamin A tells the brain that it’s daytime by translating sunlight into a signal to create more serotonin. When it’s late and less of this signal comes through, the brain creates more melatonin. Without vitamin A, this function is impossible.

However, you can take too much vitamin A, known as chronic hypervitaminosis A. In a study by Rune Blomhoff, one of the many symptoms of chronic hypervitaminosis A is sleep disturbance.

It takes a lot of vitamin A to experience these symptoms. However, since vitamin A is fat-soluble, your body stores it over time. It’s, therefore, possible to accumulate too much in your system.

Recommended Dosage

The recommended dosage for males aged 19-30 is 900 mcg and 700 mcg for females aged 19-30.

Even going over this dosage by a small amount could cause side effects. This is because vitamin A can build up over time in the body since it’s stored in the fat.

The dosage is in mcg, not mg- a microgram is one-thousandth of a milligram and one-millionth of a gram. A dollar bill weighs exactly one gram, which is why you can weigh money and know how much there is.

2/ Vitamin B5

B vitamins are a family of vitamins: B1, B2, B3, B5, B6, B7, B9, and B12. Each of them performs a different function.

Vitamin B5 enables your body to produce two chemicals: serotonin and melatonin. These two chemicals—the first a neurotransmitter and the second a hormone—are responsible for maintaining the body’s natural sleep cycle.

The body produces serotonin in the morning to make you feel more awake and alert. Your body is triggered by sunlight to produce it, so those blind from birth often have delayed sleep phase disorder, or DSPD. Melatonin, by contrast, makes you feel tired. Your body produces more melatonin when it’s dark.

To produce these chemicals, your body needs tryptophan. You can’t get tryptophan from dietary sources; your body needs to produce it internally and to produce it, you need vitamin B5.

However, your body can produce too much of either chemical in response to ingesting too much vitamin B5. If you ingest too much, you won’t be able to sleep. When you’re asleep, vitamin B5 can cause vivid dreams and nightmares.

Recommended Dosage

The recommended daily dosage of vitamin B5 is 5 mg for men and women.

3/ Vitamin B6

Vitamin B6 synthesizes dopamine, which is an important neurochemical.

Dopamine makes you feel happy and alert, which is one way that B6 can keep you awake. However, dopamine doesn’t just give you a fleeting feeling of happiness. It’s also important for your complete mental health.

Aside from assisting normal dopamine function, vitamin B6 helps the body create energy. Without vitamin B6, the body is unable to metabolize glucose. The process—known as ‘glycogenolysis’— is how the body creates glucose.

When you eat sugars, your body transforms unstable glucose into stable glycogen. It can then access the energy later by transforming it back into glucose. Without vitamin B6, this process is impossible.

The same applies to how the body accesses energy stored in fat. Vitamin B6 helps you store energy in fat. With more glucose in your system, you’ll feel energized and alert.

Recommended Dosage

Many food manufacturers add vitamin B6 to their foods. This process is called fortifying, and it’s common for vitamins B6 and B12, among others. So, it’s rare for somebody to lack vitamin B6.

Both men and women need 1.3 mg of vitamin B6 per day.

4/ Vitamin B12

Does vitamin b12 keep you awake at night? Indeed, it does. Again, it can keep you awake by making you feel more energized, so B12 (and B complex supplements) should be taken in the morning.

The vitamin B12 found in supplements is produced by bacteria, which are the only natural sources. However, since animals store vitamin B12 in the liver and muscles, you can find it in a meat-rich diet.

Vitamin B12 promotes the healthy function of the nervous system and creates red blood cells. Because of this unique function, B12 helps to prevent anemia, one of the symptoms of which is fatigue. More red blood cells also mean that your brain has access to more oxygen, making you feel more alert.

There isn’t much scientific evidence about what happens if you ingest too much vitamin B12. Similarly, there’s no research on what happens when you take vitamin B12 too late at night.

That being said, anecdotal evidence suggests it can keep you awake. The same people say that it gives them energy and makes them feel more awake.

Recommended Dosage

The recommended dosage of vitamin B12 depends on your health and diet.

Certain diets, especially vegan and vegetarian diets, are much lower in B12 than others. If so, it’s recommended that you take a vitamin B12 supplement or eat foods fortified with vitamin B12.

Pernicious anemia is possible, making it harder for your body to absorb vitamins like B12.

The recommended amount of vitamin B12 per day is 2.4 mcg for men and women.

5/ Vitamin C

Vitamin C might be one of the vitamins you expect to find in this list. You’ve probably heard that it can keep you more energized. Unfortunately, scientists are divided on whether that’s true.

A study by the International Journal of Sports Medicine found that marathon runners who took vitamin C (versus those that took a placebo) didn’t have any extra energy before, during, or after running a marathon.

However, other studies suggest that it makes you feel more awake. Another study in a Nigerian physiological Journal found that vitamin C reduced stress and fatigue levels in sleep-deprived rats.

While it doesn’t give you any physical energy, it stops you from feeling as tired as you should after sleep deprivation. It also enables the cells to produce physical energy, making you feel more alert.

If you take a large dose of vitamin C before bedtime, you’ll feel less like sleeping and be more energized.

Recommended Dosage

Vitamin C isn’t naturally synthesized in the body, but that doesn’t stop the body from needing a lot of it. It’s difficult to ingest too much vitamin C (hypervitaminosis C) because the body flushes out any extra.

Men need 90 mg, and women need around 75 mg of vitamin C per day.

6/ Vitamin D

Does vitamin D keep you awake at night? Unfortunately, vitamin D is a known cause of sleeplessness.

Most people don’t need to take a supplement for vitamin D. Unlike other vitamins, vitamin D isn’t just a nutrient that you get from your diet. In fact, the human body produces vitamin D from sunlight.

Unfortunately, vitamin D deficiency is a global health problem due to our lifestyles. It’s so common that a study in the International Journal of Health Sciences called it an epidemic.

Because of our collective lack of vitamin D, it’s difficult to take too much unless you take more than the RDA through supplements. When your body gets too much vitamin D before bedtime, it has a remarkable effect.

It makes your dreams far more vivid and encourages lucid dreaming. This is where you can control your dreams and dream about whatever you want.

These vivid dreams aren’t a negative side effect per se. As such, there has been no research so far on the topic. Vivid dreams can cause you to have a less restful night’s sleep.

Recommended Dosage

The body needs very little vitamin D. It would be impossible to get too much vitamin D from sun exposure. However, if you take certain supplements with vitamin D, it’s more likely to happen.

Some people are more susceptible to hypervitaminosis D and can develop hypercalcemia.

Both men and women need 15 mcg of vitamin D per day.

Vitamins that cause sleeplessness

7/ Vitamin K

Vitamin K is last on the list because it may cause sleepless nights for some, but not for others.

Without vitamin K, blood clotting would be impossible. A deficiency causes symptoms similar to hemophilia, where cuts or scrapes continue bleeding without clotting.

Vitamin K is formed in leafy, green vegetables. The body’s bacterial gut flora then converts it into various forms. As one of the lesser-known vitamins, few people actively seek vitamin K supplements. However, those that do may find that it can cause a stress reaction if you take too much. The reasons for this are unclear.

Anecdotal evidence points to the fact that vitamin K2—one of the several forms of vitamin K—can make you sleepier, as opposed to more alert. Unfortunately, all we have to go on is opinion rather than fact.

Scientists have only studied vitamin K’s health benefits. No attention has been paid to whether it keeps a person awake since this is less important. So, you’d need to take vitamin K to see which effect it has on you.

Recommended Dosage

The body needs little vitamin K. You can easily get enough from your diet by eating more vegetables. However, it’s also a common addition to general supplements.

Over the course of a normal day, men need 120 mcg, and women need 90 mcg.

Which Vitamins Can You Take at Night?

Vitamins not listed here are fine to take at night. These include the other B complex vitamins: B1, B2, B3, B7, and B9.

However, since supplements normally contain all of the B complex vitamins, there’s little point in taking just these five at night and the others in the morning. It’s far simpler to take a general B complex vitamin early on in the day.

Vitamin E

There’s little evidence that vitamin E keeps you awake at night. Rather, it’s a sleep aid. It combats restless leg syndrome, enabling people with this condition to sleep much better.

Some people claim that it relaxes them and makes it easier to sleep. However, it must be stressed that this evidence is anecdotal, and there’s no research on the effects of vitamin E on sleep.


Much depends on which vitamins are a part of the supplement. If there are a number of the vitamins from the above list—which is likely—they could combine to keep you awake.

The scientists behind a study in the Journal of Sleep Medicine suggested that the various vitamins could be interacting with one another to exacerbate these effects. However, their study was inconclusive as to whether this was the case.

All you have to do is take your supplements in the morning rather than at night. This will help you avoid sleepless nights, but it’s better for you. Your body better absorbs supplements if you take them in the morning because you have them with your breakfast.

Taking supplements on an empty stomach just before bed reduces their efficacy. This is because vitamins and minerals are either fat-soluble or water-soluble. Therefore, taking them with a meal that contains water and fat dissolves them.

Considering that the solution is so simple, the fact that some vitamins keep you awake isn’t a problem. All you have to do is make some minor lifestyle changes to avoid this problem entirely.