What the Hell Is Light Therapy and Does It Really Work?

In high school, Kristen Inman, now 23, started noticing patterns in her mood.

Struggling with undiagnosed depression, anxiety and self-harm, she became more conscious of how the seasons affected her. “I noticed that things typically got worse as the weather got colder and the days got shorter,” she says.

Like Inman, about 5 percent of the U.S. population experiences a form of seasonal mood disorder and depression known as seasonal affective disorder, or SAD. People affected by SAD typically experience symptoms like fatigue, hopelessness and withdrawal for about 40 percent of the year, particularly during the winter, according to a 2012 study.

One popular treatment for SAD? Light therapy, a process that involves exposure to a lamp that mimics sunlight to improve your mood. While light therapy may sound like a gimmick (at least, it did to me), it actually works — if used properly, says Kathryn Roecklein, an associate professor of psychology at the University of Pittsburgh who has studied SAD.

What to know about SAD

SAD isn’t just the “winter blues,” which involves feeling fatigued and less interested in typical activities during colder months. Also known as “subsyndromal SAD,” the winter blues is much more common, affecting about 14 percent of U.S. adults, but they don’t technically meet the current medical criteria for SAD, Roecklein says. SAD is more serious than that. In fact, it’s considered a subset of clinical depression, not a separate disorder, Roecklein says.

“Unlike major depression, though, SAD is characterized by its predictability: It sets in when the seasons change — usually from summer to winter — and it returns in the same pattern for at least two years in a row,” she says. “A person with SAD will experience consistent depressive symptoms most of the day for at least two weeks.”

Symptoms of SAD usually occur during the fall and winter months when there’s less sunlight, particularly in January and February for those in the U.S. Some people also experience SAD in the summer, but that’s less common, according to the American Psychiatric Association. For people who experience SAD, symptoms can affect daily routines and functioning.

“I feel tired and unmotivated but have trouble falling asleep because I’m also agitated,” Inman says. “It alleviates in the spring, which, like last year, could be as early as February or sometimes as late as April.”

Researchers still don’t know the exact causes of SAD, but there is a strong correlation between SAD and sunlight, Roecklein says. “Some of this can be attributed to daylight saving time. When it gets darker earlier, our bodies produce more melatonin, a hormone that regulates sleep, which can throw off circadian rhythms, leaving people feeling more tired than usual.”

Certain people are more likely to experience SAD: those who live closer to the poles than in climates with less seasonal change; those with a family history of depression and SAD; women, who are four times more likely to report having SAD than men; and children and teens.

Light therapy and how it works

The use of light therapy to treat SAD is relatively new. Researchers coined the term seasonal affective disorder in 1982 and two years later discovered it could be effectively treated with bright therapeutic light.

In the years since, research has continued to confirm that light therapy can be effective. The treatment requires you to sit in front of a 10,000-lux light box (that’s about 100 times brighter than normal indoor lighting) for 20 minutes to an hour first thing in the morning every day during the months you experience SAD, Roecklein says. The idea is to replace the natural sunlight you’re not getting.

Inman has been using light therapy successfully for years, but she was skeptical at first. “I read about light therapy online during the fall of my junior year of college, but I didn’t initially purchase one because they were expensive to me, and I was not sure if they worked in the first place or if it was some sort of pseudo-science fad or placebo,” she says.

But she was seeing a licensed counselor and a psychiatrist by that point, so she asked her psychiatrist: Does it really work? “He reassured me that the science behind them had merit and recommended that I try one. By that winter, if I was sitting at my desk at home, the light box was also on.”

Because it requires a time commitment each day and a routine, a study conducted by Roecklein found that only about 12 percent of people with SAD who are given a light box will actually continue using it the next winter. “Light therapy can be effective if done properly, but it must be used as directed, every day, in order to feel its full effects,” Roecklein says. When used correctly, the treatment can take effect within a week. However, even for those who try it, it’s not a guarantee. Research has found about a 50 percent chance that a dawn simulator — a timed light that gradually increases in intensity early in the morning — or a light box will work as a treatment for SAD, Roecklein says.

If you experience SAD, though, it’s worth trying. Inman still uses a light box, along with increased medication and vitamin D supplements, with success. “I’m going on two and a half years free of self-harm, and I’ve become proactive about my ‘winter’ needs,” she says.

Likewise, Eileen Cotter Wright, a 32-year-old American living in London, says “the glow of the SAD light brightened up my room and gave me more than just light therapy. I was doing something productive, actionable, to try to feel better. While working from home, it gave me routine and a daily task to accomplish, which also helped morale. I love the SAD therapy and almost feel bummed when it’s time to put it away for the spring.”

For those suffering from subsyndromal SAD, or the winter blues, light therapy could work for them, too. But treatment — even light therapy, which doesn’t require a prescription — should be discussed with a doctor, Roecklein says. “The reason is that light has similar effects in the brain as medication, and surely no one would start antidepressant medication treatment for depression without a doctor, even if their symptoms were less severe.”

Other treatments exist

Sticking to a daily routine of sitting near a light for a certain amount of time probably isn’t for everyone. Plus, light boxes can be pricey. Thankfully, other treatment options exist for SAD, including anti-depression medication and cognitive behavioral therapy. “These therapies have the patient identify negative thoughts and work to replace them with more positive, self-serving ways of thinking and behaving,” Roecklein says.

The treatments can be used individually or together.

Vitamin D, though popular among those who experience SAD, has had inconclusive research results as a form of treatment compared to light therapy, Roecklein says. “People with SAD often have low levels of Vitamin D, which could be caused either by lack of sun exposure or by not getting enough of it in their diet. Vitamin D isn’t currently recommended by itself as a sufficient treatment for SAD, but it can be used in combination with light therapy, medication or psychotherapy.”

For Inman, the combination of three treatments — light therapy, increased medication and vitamin D — has worked, and she thinks light therapy specifically has made all the difference. “Even though I still feel the effects of SAD, they are milder than they would be without it,” she says. “It makes me feel better, during times when I miss the sunlight, to have my own personal sun.”

Gif/collage by Edith Young. Photo via Arthur Elgort/Conde Nast/Getty Images.

Julissa Treviño

Julissa Treviño is a writer and journalist who has been published in Columbia Journalism Review, The Dallas Morning News, Racked, CityLab and The Development Set. Follow her @JulissaTrevino.

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