Narcolepsy is a rare sleep disorder that can cause excessive daytime sleepiness, sudden loss of muscle tone (cataplexy), sleep paralysis, and hallucinations. Typically, narcolepsy develops when there is a shortage of a hormone called hypocretin (also known as orexin). Hypocretin is a neurotransmitter (a chemical that nerve cells called neurons use to communicate) that is produced by a part of the brain called the hypothalamus. This hypocretin shortage could be caused by family history, a brain injury, or autoimmune conditions (when the immune system mistakenly attacks the body).

However, research shows that other biological factors could contribute to narcolepsy. One hypothesis is that a deficiency (lack of) of certain vitamins, such as vitamin D and vitamin B12, may be risk factors for the development and severity of narcolepsy.

This article discusses the research-based evidence on what vitamin deficiencies, if any, can be predictors of or contributing factors to narcolepsy. It also discusses what to do if you suspect you are deficient in any vitamins. Always talk to your doctor before taking vitamin supplements at home.

Vitamin Deficiencies and Narcolepsy

There are many reasons why someone with narcolepsy may have a vitamin deficiency. People with narcolepsy experience eating disorders at a higher rate than the rest of the population. They may not be getting enough nutrition through regular, healthy meals. Low vitamin D levels can be common in people with mental health issues, irregular sleep schedules, or inactive lifestyles. In addition, general absorption issues can lead someone to be nutritionally deficient despite a healthy diet. For this reason, if you are experiencing symptoms of a nutritional deficiency, ask your doctor for a blood test to determine what changes to your diet or nutritional supplementation might be necessary.

Vitamin B12

Vitamin B12 is a water-soluble vitamin that can be found in meat, eggs, and dairy products. It is stored in the liver and used for many bodily processes, particularly in forming new DNA, creating the building blocks of fat, and certain types of protein.

Vitamin B12 deficiency can have one of three causes. It can be due to a lack of vitamin B12 in the diet, which is a major concern for vegans and some vegetarians. It can also be caused by an autoimmune issue that prevents the body’s absorption of vitamin B12. Finally, digestive impairment such as irritable bowel disease can prevent absorption of vitamin B12 and cause it to be excreted before being used by the body.

A vitamin B12 deficiency often leads to pernicious anemia, which is a decrease in the body’s red blood cell count. This condition can lead to cognitive impairment, light-headedness, tiredness, depression, memory loss, and even heart and nerve damage. If you suspect that you have a vitamin B12 deficiency, your doctor can take a blood test — including a complete blood count, serum levels of vitamin B12, and a blood smear — to decide on the best course of treatment.

So, is vitamin B12 deficiency also linked to narcolepsy? Results are unclear. One study that compared blood vitamin B12 levels between 40 patients with narcolepsy and 40 healthy controls showed slight but statistically significant increased odds that a person with narcolepsy had a B12 deficiency, after controlling for all other variables. Although there are a few other case studies of people with narcolepsy who have vitamin B12 deficiencies, there are no large, controlled studies that can verify these results. Therefore, a vitamin B12 deficiency may be associated with narcolepsy in some way, but there is no clinical explanation for this mechanism yet.

Vitamin D

Vitamin D is a fat-soluble vitamin that is crucial for many daily bodily functions. For example, vitamin D absorbs calcium, which helps to build bones in the body. It does this by working with the parathyroid glands (located in the neck) to regulate levels of calcium in the blood. Without vitamin D, calcium is not able to do its job. Vitamin D deficiency is related to a higher prevalence of many health conditions, including immune system dysfunction, heart disease, diabetes, bone fractures, cancer, and multiple sclerosis.

Spending 20 minutes in the sun, three days a week, usually allows the body to produce enough vitamin D. However, the more melanin your skin has, the darker your skin will be, and more sunlight is needed to produce enough vitamin D. Sunlight may be hard to come by depending on where you live, the time of year, your occupation, and other factors. Luckily, you can also get vitamin D from your diet, through foods like salmon, tuna, fortified orange juice and milk, and egg yolks. When all else fails, taking vitamin D supplements (with the guidance of your physician) can help regulate vitamin D levels year-round.

A 2018 systematic review and meta-analysis showed that a small number of high-quality, peer-reviewed research articles have been published showing that those with a vitamin D deficiency have 1.5 times the risk of developing sleep disorders. Vitamin D deficiency is specifically associated with worse sleep quality, shorter nighttime sleep duration, and increased daytime sleepiness. However, this review did not report on research specific to narcolepsy — it reported on other sleep disorders such as obstructive sleep apnea, hypersomnia, and insomnia. It also suggested that additional randomized controlled trials are necessary to strengthen this association.

One specific case-control study from 2011 matched people with narcolepsy to people without and showed an increased risk of vitamin D deficiency in those with narcolepsy. However, another, larger case-control study from 2017 with the same methods showed no association between vitamin D deficiency and type 1 narcolepsy. Either way, the mechanisms for a relationship between vitamin D deficiency and narcolepsy have not yet been confirmed in a large, controlled trial.

What Does This Association Mean?

Overall, there is some evidence that vitamin deficiencies may play an important role in disturbances to the sleep-wake cycle. Just because a deficiency has been found to be linked to narcolepsy in small observational studies does not mean that a deficiency causes narcolepsy, or that correcting the deficiency will improve your condition. Whether or not your vitamin deficiency is playing a role in your sleep condition, treating it can improve your overall wellness and quality of life.

If you have a vitamin deficiency, treatment for this can supplement your current narcolepsy treatment regimen. Treatment for a vitamin deficiency varies on the type of vitamin. Vitamin B12 is usually injected by a health care provider every two weeks or prescribed as a supplement in tablet form. Vitamin D supplements can be taken as a daily pill, found over the counter or by prescription. Before taking any supplements, talk with your physician to be properly evaluated if you suspect a vitamin deficiency. Make sure to follow your doctor’s orders to see what dosage and frequency of dietary supplementation they recommend.

Talk With Others Who Understand

On MyNarcolepsyTeam, the social network for people with narcolepsy and their loved ones, more than 9,000 members come together to ask questions, give advice, and share their stories with others who understand life with narcolepsy. Here, finding out more about the causes of narcolepsy to improve quality of life is a commonly discussed topic.

Have you ever been tested for a vitamin deficiency? Do you take nutritional supplements as recommended by your doctor? Share your experience and advice in the comments below, or start a conversation by posting on your Activities page.