Does Vitamin D Help With Seasonal Affective Disorder?

The gloomy days of winter don’t just yield to frigid temperatures. For some, it’s also the time of year where seasonal affective disorder ― or even just bouts of the winter blues ― can disrupt their daily lives, leaving them searching for a fix.

One popular method for treating SAD is vitamin D, which most people naturally get from their diet and especially sunlight (something the wintertime very clearly lacks). It’s believed that vitamin D can help manage the debilitating symptoms of the mental health condition, which include a lack of motivation, changes in sleep patterns, increased irritability and sadness.

But does it really, truly work? According to experts, we can’t definitively proclaim that it does. Vitamin D’s “possible role in mental health symptoms has been explored with mixed results,” said Shari Harding, a professor of nursing at Regis College in Massachusetts and an expert on SAD.

A very small study published in 1999 stated that SAD can occur when vitamin D storage in the body is low. It found that the vitamin could possibly be useful in treating symptoms of the disorder, but noted that more research was needed.

A 2014 study published in the journal Medical Hypotheses suggested that low vitamin D could contribute to the development of SAD. The study authors said vitamin D can play a role in the production of serotonin and dopamine, the “happy chemicals” in the brain that are often low when someone has depression. However, another study published in 2014 by Danish researchers found that vitamin D supplementation didn’t directly improve SAD symptoms.

A meta-analysis published in 2018 also found a correlation between lower vitamin D levels and depression, the BBC reported, but that doesn’t necessarily mean it’s the cause of the illness. It just indicates that the two existed at the same time. (Since a symptom of depression is withdrawal, it’s possible that those living with the illness didn’t go outside enough to get normal amounts of vitamin D, the BBC pointed out.)

Given that SAD is a complex illness, experts can’t solely pin its presence on a lack of vitamin D. Mental health disorders usually develop because of a person’s environment, circumstances, physiology or a combination of these items.

“There is evidence that some people with depression may also have vitamin D deficiency, but it is not clear what role the deficiency plays in depressive symptoms,” Harding said. “There are many factors that affect symptoms of depression, so the best evidence at this point supports having your vitamin D level checked by a health care provider.”

You’re typically able to get the recommended levels of vitamin D ― which is good for bone health ― by going about your everyday life, Harding said. This includes causal sun exposure and consuming foods and drinks that contain vitamin D, such as milk, cereal and salmon.

“People who live in climates where it gets darker earlier are at risk of not getting enough vitamin D without supplementing, but vitamin D is a fat-soluble vitamin, so it is possible to supplement too much and reach toxic levels,” Harding said. “The best way to approach vitamin D is to have your level checked and then talk to a health care provider about the best plan for you.”

What experts do know about SAD is that it can be exacerbated by a lack of light, which is why it’s more prevalent in more northern parts of the U.S. where there isn’t as much sun during the winter. Those who experience the winter blues or SAD have enjoyed some success in reducing its effects with light therapy ― exposure to artificial light through a device that mimics what you’d receive outdoors. Light therapy is “thought to affect brain chemicals linked to mood and sleep, easing SAD symptoms,” according to the Mayo Clinic.

Bottom line, if you’re experiencing any problems with your mental health ― at any point during the year ― it’s important to acknowledge it and speak up. Some warning signs include a difficulty to complete normal tasks, withdrawal from social activities, changes in mood or behavior and disruptions in eating or sleep patterns. These are all particularly alarming if they interfere with your daily life.

“The most important thing to know about SAD is that it should not be underestimated in terms of its severity or impact. It is a type of depression,” Harding said. “People who believe they may have SAD should absolutely seek treatment and should not rely solely on lifestyle changes to manage symptoms. Untreated or under-treated depression can cause serious problems, but sometimes people hesitate to seek treatment.”