I suffer from insomnia. Recently, my treating physician prescribed me vitamin B12 but I don't really understand why and I am wondering whether this is due to my insomnia.

So my question is: does vitamin B12 deficiency cause insomnia or on the contrary, is vitamin B12 caused by insomnia?

  • 2
    Hi! May I ask what your doctor told you when he prescribed you vitamin b12? And as a side note, could you edit your question, there are some words missing and some rephrasing needed. Thanks
    – Felipe
    Sep 20, 2016 at 18:48
  • He told me I must sleep for eight to ten hours.
    – user2519
    Sep 20, 2016 at 18:57
  • 2
    Ok but what did he tell you when he prescribed you vitamin b12? He must have given you a reason? And can you edit your question please? In the moment it is hard to read... Thanks! Cheers
    – Felipe
    Sep 20, 2016 at 19:20
  • He didn't told me anything but, he guess I'm not sleeping very well. So I though I've vitamin B12 deficiency because of sleeplessness.
    – user2519
    Sep 21, 2016 at 5:24

1 Answer 1


Vitamin B12 is involved in the synthesis of melatonin, a hormone that is produced by the pineal gland in mammals and helps to regulate the circadian rhythm and therefore sleep. Thus a B12 deficiency could result in sleep disturbance.

enter image description here Source:

Peuhkuri, Katri, Nora Sihvola, and Riitta Korpela. "Dietary factors and fluctuating levels of melatonin." Food & nutrition research 56.1 (2012): 17252. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3402070

This provides a theoretical basis for the treatment of sleep disorders with B12, however the evidence base for the efficacy of such treatment is very small, consisting mainly of low-quality epidemiological studies (case reports). The only well-designed study I could find was by Okawa el at (1997) which did not find any treatment effect:

Okawa M, Takahashi K, Egashira K, et al. Vitamin B12 treatment for delayed sleep phase syndrome: a multi-center double-blind study. Psychiatry Clin Neurosci. 1997;51:275–9.


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