If you take a look at energy supplements or energy drinks, there’s one ingredient you’ll find in common—vitamin B12. Along with its brothers and sisters in the B family, B12 plays a significant role in the energy production cycle, hence why it’s a staple in most energy boosters.

But on top of supporting energy, getting enough B12 is required for the production and maintenance of healthy red blood cells, supporting proper neurological function, and maintaining a healthy nervous system.

While most people get enough B12 through diet, for some vegans and vegetarians, keeping your levels up is challenging, so supplementation is necessary. But when you’re supplementing, being mindful of when you take your B12 is key to maximizing its effects—and your sleep.

We’re giving you what you need to know about B12 and energy production and why taking B12 at night could keep you awake.

The Role Of Vitamin B12

Vitamin B12 is one of the nine water-soluble vitamins that plays a critical role in several biological functions, ranging from red blood cell health and energy production to DNA synthesis and nervous system health.

B12 also plays a significant role in preventing vascular and cognitive diseases through its involvement in the conversion of homocysteine to methionine and then to S‐adenosyl‐methionine. In this cycle, it serves as a cofactor to allow conversion, so a deficiency of B12 or folate can interfere with the conversion and lead to a buildup of homocysteine 1.

However, in order for your body to absorb vitamin B12, you need sufficient amounts of a protein called intrinsic factor, which is produced by parietal cells of the stomach.

Intrinsic factor forms a complex with vitamin B12, thereby allowing it to enter the bloodstream and systemic circulation. So, while you may be consuming enough dietary B12, what you’re actually absorbing depends on your levels of intrinsic factor.

That said, sublingual supplementation and intramuscular injections both bypass gastric absorption and may have higher efficacy rates.

Vitamin B12 And Energy Production

Aside from anemia, one of the most prominent symptoms of low vitamin B12 is fatigue because of its role in supporting red blood cell formation and oxygen transport.

In order for your cells to function optimally, they require sufficient delivery of oxygen and nutrients and there is a big interplay between vitamin B12, folate, and iron for erythropoiesis (red blood cell formation) 2.

Red blood cells are constantly undergoing regeneration. Old red blood cells are destroyed and engulfed to make room for new, healthier, and more functional ones.

But the process of erythropoiesis is dependent on three nutrients: B12, folate, and iron. A deficiency of any one impairs blood cell formation and can lead to the formation of abnormal blood cells that can’t effectively carry oxygen. The result is low energy and fatigue 3, 4.

That’s why supplementation with B12 leads to more efficient oxygen transport and higher energy levels. But when you take your B12 supplement is important.

Should You Take Vitamin B12 At Night?

Ideally, no. While there is no scientific evidence recommending against taking B12 at night, because of its role in energy production, it can elicit a stimulatory effect in some people, as do the other B vitamins.

That said, there is evidence showing vitamin B12 regulates the sleep-wake cycle by supporting synchronicity of the circadian rhythm 5. But at the same time, the evidence behind the link between B12 and sleep isn’t completely clear.

Studies show a connection between insomnia and levels of B12, while other studies show that high levels of B12 can lead to increased sleep disruptions and a shorter sleep duration 6, 7.

To keep yourself safe from any adverse effects, take your B12 supplement in the morning or early afternoon to prevent any potential disruption to sleep.

Final Thoughts

Although there are no guidelines suggesting the recommended time to take vitamin B12, and there is no clinical evidence showing a link between B12 supplementation at night and sleep disruption, it does have the potential to disrupt sleep.

If you’re taking a nighttime dose of B12 and notice any persistent negative changes to your sleep, pushing your supplementation forward earlier in the day may be ideal.


  1. Oh R, Brown DL. Vitamin B12 deficiency. Am Fam Physician. 2003;67(5):979-986.
  2. MJ Koury, P Ponka. New insights into erythropoiesis: the roles of folate, vitamin B12, and iron.Annu Rev Nutr. 2004;24:105-131.
  3. A Hariz, PT Bhattacharya. Megaloblastic Anemia. (Updated 2021 Oct 11). In: StatPearls (Internet). Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537254/
  4. A Ankar, A Kumar. Vitamin B12 Deficiency. (Updated 2021 Jun 7). In: StatPearls (Internet). Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441923/
  5. Okawa M, Mishima K, Nanami T, et al. Vitamin B12 treatment for sleep-wake rhythm disorders. Sleep. 1990;13(1):15-23.
  6. Djokic G, Vojvodić P, Korcok D, et al. The Effects of Magnesium - Melatonin - Vit B Complex Supplementation in Treatment of Insomnia. Open Access Maced J Med Sci. 2019;7(18):3101-3105.
  7. Beydoun MA, Gamaldo AA, Canas JA, et al. Serum nutritional biomarkers and their associations with sleep among US adults in recent national surveys. PLoS One. 2014;9(8):e103490.