| As a clinical psychology graduate student working in a depression lab in Maine in the 1990s, Kelly Rohan found it much easier to recruit depressed patients in the winter. What, she wondered, was going on? Nearly three decades later, we’ve all heard of seasonal affective disorder, but back then, it was a new concept. In the vernacular, people talk about the condition as the winter blues: There’s less sunlight in the colder months, which makes people sad. (I can’t claim credit for the pun.) Where Rohan lived at the time, the shortest day of the year saw less than 9 hours of sunlight. Officially, SAD is a type of depression, one that gets worse in the winter and better in the summer. But many people without a full-blown diagnosis still experience a seasonal shift in mood, says Rohan, who is now a professor of psychological science at the University of Vermont. Rohan has been studying the condition over the past three decades, examining potential treatments. Some of them are same ones used to treat regular depression, namely medications and cognitive behavioral therapy. Because SAD is related to sunlight, there’s another option: light therapy. But while it often helps, Rohan says, “nobody really knows how it works.” It’s thought that because special light boxes simulate sunlight, they can encourage brains to reduce sleep-inducing melatonin and increase serotonin, which can elevate mood. Studies have shown that sun lamps can help, even for people only have a mild form of the condition. But science is not exactly sure why. That’s why Rohan is doing research. By gathering biological data, like information on pupil reactivity, brain activity, and hormone levels in saliva, she hopes to better understand how sun lamps can be helpful. Rohan warns that light therapy isn’t as simple as going to the store and buying a sun lamp. She advises working with a doctor to find the right product and to work out a dosing schedule. She also points out that while light therapy can be helpful when someone is actively doing it, cognitive behavioral therapy can give people skills to manage their depression in the long-term. Getting sunlight the natural way is never a bad idea, she adds. Taking a walk in the morning gets you exercise and sun, killing two birds with one stone. — Ike Swetlitz | 
