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Does Vitamin B12 Deficiency Cause Insomnia?

by Dale Cudmore | Updated: May 25, 2023

Vitamin B12 deficiency is common in vegetarians and older people.

It is responsible for a variety of neurological health problems.

While it’s not overwhelming, there is some evidence that vitamin B12 deficiency may indirectly cause insomnia in some people. Other B-vitamins like niacin are also important for sleep.

We’ll review that research quickly in this post.

Symptoms of Vitamin B12 Deficiency

Vitamin B12 deficiency rarely has physical symptoms. Most common side effects are considered psychiatric or neurological symptoms, which includes (1):

  • Irritability
  • Personality change
  • Mild memory impairment (dementia)
  • Depression
  • Psychosis

Since we’re considering sleep quality in particular, depression is the big symptom we’re concerned with.

Do B12 Deficiency Symptoms Lead to Insomnia?

There’s not a ton of research specifically on this topic, but we’ll look at what we can.

One study looked at the level of vitamin B12 and D in children with an autoimmune disorder (2).

They found that there was not a significant correlation between low vitamin B12 levels and most sleep quality metrics.

However, sleep efficiency (percent of time in bed actually asleep) was lower in vitamin B12 deficient patients.

While this is a single study that you can’t take too much away from, it shows that vitamin B12 may have some direct influence on sleep quality, but not too much.

Another study on the elderly found that overall malnutrition, not B12 deficiency, predicted insomnia severity (3).

SummaryIt appears that vitamin B12 deficiency doesn’t cause insomnia for most sufferers. But there could be some groups of people (i.e. that go on to develop depression) that ultimately suffer worse sleep because of the B12 deficiency.

Depression and Insomnia

There’s strong evidence linking vitamin B12 deficiency to depression (4).

And there’s also strong evidence linking depression to insomnia (5). It’s one of the biggest risk factors of insomnia, alongside stress.

SummaryNot all people with vitamin B12 deficiency will develop depression symptoms, but those who do are at high risk of developing insomnia as a result.

Restless Leg Syndrome and Vitamin B12

Like the name of the condition suggests, Restless Leg Syndrome (RLS) is a condition where your legs can’t stay still at certain times.

RLS can of course make it harder to sleep and play a role in developing insomnia.

While RLS is usually caused by iron deficiency, there’s some evidence linking vitamin B12 deficiency and RLS (6).

SummaryIt’s not a particularly likely scenario, but there appears to be some small chance of a vitamin B12 deficiency triggering RLS and leading to sleep trouble.

Treating Vitamin B12 Deficiency

This is one of the easiest underlying causes of psychological disorders to fix. An oral or injectable B12 supplement will fix the deficiency and clear up most symptoms.

One study split depressed patients who had low B12 levels into 2 treatment groups (7):

  • Antidepressant
  • Antidepressant plus vitamin B12 injection

They found:

Vitamin B12 supplementation with antidepressants significantly improved depressive symptoms...

So while a doctor will likely prescribe treatment for depressive symptoms, they should also consider recommending a B12 supplement.

Summary: Vitamin B12 and Insomnia

The main way that vitamin B12 deficiency can cause sleep issues is by first causing depressive symptoms, which are strongly linked with insomnia.

If someone with a vitamin B12 deficiency doesn’t have depressive symptoms, current research suggests that it’s not likely to cause sleep issues (although there are other non-sleep related side effects). This is unlike other nutrients that can cause insomnia directly like a calcium deficiency, or a vitamin D deficiency.

Treatment for B12 deficiency and any resulting symptoms should always be planned by a doctor, which will likely include a vitamin B12 supplement and possibly other symptom-specific treatment.


  1. Vitamin B12 Deficiency
  2. Decreased serum vitamin B12 and vitamin D levels affect sleep quality in children with familial Mediterranean fever
  3. Relationship Between Nutritional Status and Insomnia Severity in Older Adults
  4. Mood disorder with mixed features due to vitamin B12 and folate deficiency
  5. Risk Factors for Incident Chronic Insomnia: A General Population Prospective Study
  6. Iron, vitamin B12 and folate
  7. Vitamin B12 supplementation in treating major depressive disorder

Medical Disclaimer: The information on is not intended to be a substitute for physician or other qualified care. We simply aim to inform people struggling with sleep issues about the nature of their condition and/or prescribed treatment.

About the authorDale is the founder of Snooze University and a sleep researcher. I overcame my sleep issues and now I'd like to help you do the same by summarizing the latest sleep studies for you.