Vitamins That Keep You Awake at Night

7 Really Surprising Vitamins That Keep You Awake at Night

There are few things worse than not being able to sleep at night. Unlike other problems, there’s never one easy solution. If you have an aching neck and shoulder, you can use painkillers or massage to make the pain go away. But, if you’re not sleeping right, there are dozens of different things that might be causing your problem.

What most people don’t appreciate is that something as simple as vitamin supplements can cause sleepless nights. Since vitamins are essential nutrients that your body needs to function, it sounds counterintuitive. Surely, they couldn’t cause insomnia, or lead to severe side effects like pharmaceuticals?

Well, they can, and do! Vitamins can cause insomnia. They can also cause nausea, diarrhea, muscle cramps, and more. However, it’s not the vitamins that are the problem.

The problem is if you go over the recommended daily allowance (RDA). You can have too much of a good thing. You also have to make sure that you take them early in the morning with food. Otherwise, they can have unintended effects.

The first section below is on why vitamins can have such an unexpected effect. Afterward, we’ve provided a list of which vitamins make you alert at night, and which don’t. Read on if you’d like to know more.

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, when it comes to hard scientific evidence, there’s very little information out there. Only a small number of studies have been done on which vitamins keep you awake, and why.

The most important study was published in the Journal of Sleep Medicine. It was a medium-scale experiment on hundreds of US citizens that sought to determine whether taking a vitamin or mineral supplement had any effect on sleep amount or sleeping patterns.

They found that ‘use of a multivitamin or multiple single vitamins was associated with poorer sleep maintenance compared to individuals who did not take vitamin supplements.’ Put simply, taking vitamins seems to make you sleep worse. What they didn’t know was why. They suggested that it could be because:

  • Vitamin use causes poor sleep in certain individuals, i.e. because of 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 combat their conditions

In other words, they weren’t sure exactly why people taking vitamins sleep worse. However, there may have been a reason that they overlooked: 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 really is no scientific consensus on the matter, and more studies need to be done.

What Vitamins Cause Sleeplessness?

There are a surprising number of vitamins that cause insomnia. In fact, there are more that do than those that don’t. But like we said above, the trick is to take them right.

You have to make sure a) that you don’t go over your RDA, and b) that you take them at the right time. This will normally solve your sleepless nights. Let’s take a look at which vitamins can keep you awake at night.

Vitamin A

So, let’s start at the top of the list. 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, which regulates (among other things) the time that we sleep. Vitamin A plays an important part in our body clock.

taking multivitamins before bed

Specifically, vitamin A plays a huge role in eye health. Not only does it keep the eye itself healthy, but everything else to do with our eyesight, too.

In basic terms, vitamin A helps tell the brain that it’s daytime by ‘translating’ sunshine 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 crucial function is impossible.

However, it’s possible to take far too much vitamin A; this is known as chronic hypervitaminosis A. As pointed out 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, this means that your body stores it over time. It’s, therefore, possible to build up how much you have in your system over weeks, months, or years.

Recommended Dosage

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

Bear in mind that 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).

Vitamin B5

B vitamins are actually a family of vitamins: B1, B2, B3, B5, B6, B7, B9, and B12. Each of these vitamins performs a different function for the body.

Among other effects, vitamin B5 helps 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.

They’re two sides of the same coin. Your body produces serotonin in the morning, to make you feel more awake and alert.

Your body is triggered by sunlight to produce it, which is why those blind from birth often suffer from delayed sleep phase disorder, or DSPD. Melatonin, by contrast, makes you feel tired. Your body produces more melatonin when it’s dark.

In order to produce both of these chemicals, your body needs plenty of ‘tryptophan’. You can’t get tryptophan from dietary sources; your body needs to produce it internally, and in order to produce it, you need B5.

However—and this is the important part—your body can produce too much of either chemical in response to ingesting too much vitamin B5. If you ingest too much, then, you can end up staring at the ceiling trying to force yourself to sleep. And later on, when you are asleep, B5 can cause vivid dreams and nightmares too.

Recommended Dosage

There are a number of different recommended dosages for B complex vitamins. That’s because there are eight of them. The recommended dosage for B5 specifically is 5mg for both men and women.

Vitamin B6

Next up is another vitamin in the B complex, vitamin B6. B6 is highly important and plays a number of roles in the body. First, it helps you synthesize dopamine, which is an important neurochemical.

Dopamine helps you to feel happy and alert, which is one way that B6 can keep you awake. But 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, B6 helps the body create energy, in a very literal sense. 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 B6, this process is impossible.

Can vitamin D keep you up at night?

The same goes for the way that the body accesses energy stored in fat. First, B6 helps you store energy in fat, and then it helps you access it later.

As you can imagine, then, taking more than your share of vitamin B6 helps your body to create energy. With more glucose in your system, you’ll feel energized and alert.

Recommended Dosage

Like other B vitamins, many food manufacturers add B6 to their foods. This process is called ‘fortifying’, and is common for vitamins B6 and B12 among others.

As such, it’s very rare for somebody to be lacking in vitamin B6. And despite it being very important, you don’t need much of it. All you need is 1.3mg per day (both men and women).

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, which is why B12 (and B complex supplements generally) are best for you if you take them in the morning.

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

B12 is incredibly important. It promotes the healthy function of the nervous system and helps create red blood cells. Because of this unique function, B12 helps 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 as to what happens if you have too much B12. Similarly, there’s no research on what happens when you take B12 too late at night.

That being said, anecdotal evidence from online reviews and guides 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 B12 supplement, or eat foods fortified with B12.

A condition called ‘pernicious anemia’ is also possible, which makes it harder for your body to absorb vitamins like B12. However, the general recommended amount is 2.4mcg for both men and women.

Vitamin C

Vitamin C might be one of the vitamins you expected to read about in this list. You’ve probably heard that it can help you feel more ‘energized’. Unfortunately, scientists are split as to 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’ either before, during, or after a marathon.

However, other studies do suggest that it helps 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 helps the cells to produce physical energy, making you feel alert.

All that being said, what does that mean for sleep? Well, if you take a large dose of vitamin C before bed, it may help you stay awake.

You’ll feel less like sleeping, and perhaps a little more energized than you otherwise would. And if you take anecdotal evidence at face value, then vitamin C is one of the worst culprits.

Recommended Dosage

Vitamin C isn’t naturally synthesized in the body, but that doesn’t stop the body from needing a lot of it. Over the course of a day, men need around 90mg and women need around 75mg.

Compared to just under 1mg of vitamin A and just over 1mg of vitamins B1 and B2, that’s a lot. It’s difficult to have too much vitamin C (hypervitaminosis C) because the body flushes any extra very quickly.

Vitamin D

Does vitamin D keep you awake at night? It most definitely does. Vitamin D is one of the worst vitamins when it comes to keeping you awake.

Normally, it has a range of positive effects: it promotes healthy bones and teeth (like calcium), supports the immune system, and supports proper cardiovascular health. It may also help prevent cancer since vitamin D plays an important role in managing cell growth.

Do vitamins give you more energy at night?

Most people don’t need to take a supplement for vitamin D. Unlike other vitamins, vitamin D isn’t just a nutrient you get from your diet. In fact, your body produces it when you come into contact with sunlight.

Unfortunately, because of our lifestyles, vitamin D deficiency is a global health problem. It’s actually so common that a 2010 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 has too much vitamin D just before bedtime, it actually has a remarkable effect.

It makes your dreams far more vivid, and even encourages so-called ‘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. However, anecdotal evidence from product reviews and posts online all suggest the same thing. It goes without saying that very vivid dreams can cause you to have a less restful sleep.

Recommended Dosage

The body needs very, very little vitamin D. It’s recommended that you have 15mcg per day. It would be impossible to get too much vitamin D from sun exposure.

However, if you take supplements with vitamin D, it would be possible, although rare. Some people are especially susceptible to hypervitaminosis D and can develop hypercalcemia in response to excess. Talk to your doctor if you aren’t sure about supplementation.

Vitamin K

Vitamin K is at the bottom of our list because it seems like it may cause sleepless nights for some, but not for others. Like all vitamins, it plays a vital role in the body.

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 search out 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.

That being said, other anecdotal evidence points to the fact that vitamin K2—one of the several forms of vitamin K—can actually 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 many health benefits. No attention has been paid to whether it keeps a person awake since this is less important. As such, you would have to try taking vitamin K to see which effect it has on you.

Recommended Dosage

The body needs precious little vitamin K. Over the course of a normal day, men need 120mcg, and women need 90mcg. You can easily find this amount in your diet by eating more vegetables. However, it is also a common additive in general supplements.

Which Vitamins Can You Take at Night?

Vitamins not listed here are perfectly 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 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 instead.

What is the best time of day to take vitamins?

Vitamin E

There is also very little anecdotal evidence that vitamin E keeps you awake at night. Rather, it’s a sleep aid. It combats restless leg syndrome, which can help sufferers sleep much better.

There are also some people who say that it relaxes them and makes it easier for them to sleep. However, it must be stressed that this evidence is anecdotal. There is no research on the effects of vitamin E on sleep.


Multivitamins have a mixed record for keeping you awake. Naturally, it 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 up.

The scientists behind the 2007 study in the Journal of Sleep Medicine suggested that the various vitamins could even be interacting with one another to exacerbate these effects, although their study was inconclusive as to whether this was the case.

There’s one simple solution that always works to combat this problem. All you have to do is make sure to take your supplements in the morning, rather than at night.

Not only will this help you avoid a sleepless night, but it’s also better for you. Your body better absorbs supplements if you take them in the morning because you have them with 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 both water and fat helps them dissolve. The quicker they dissolve, the quicker they dissolve. The quicker they dissolve, the more evenly they can be absorbed by the body.

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 a minor lifestyle change to avoid the problem completely.