While the cloudy Cambridge skies and snow-capped lecture halls may seem innocuous to many students, the belated winter weather can lead to depression for others.

Seasonal Affective Disorder (SAD) is a “fairly common problem” at Harvard during the winter months, according to Richard D. Kadison, Harvard’s chief of mental health at University Health Services (UHS).

The condition occurs when people don’t receive enough natural light, which can increase the risk of depression, Kadison wrote in an e-mail.

Kadison recommends that students coping with their melancholy seek help from the mental health division of UHS, which offers special therapeutic lights that can be signed out for a one- to two-week trial.

The harsh winter conditions brought Tatiana Wilson ’09 to UHS seeking to brighten up her life. Wilson, a native of Hawaii, signed up for a UHS light box in December.

“It was nice to have for a week, since it made our bedroom a lot warmer,” she said. “I’m not sure if it actually worked, or if it was my mind just telling me that I felt better.”

Therapeutic light boxes are perhaps the most effective way for people to uplift their sullen moods, experts say. Some boxes contain a specially designed light that is ten to forty times brighter than normal room lighting.

Studies have shown that blood levels of the hormone melatonin are stifled by contact with bright light boxes. High melatonin levels may be responsible for lower body temperatures, which can cause a person to feel less energetic.

Kadison said that light therapy for one or more hours each day can help alleviate symptoms. Antidepressant medication may also be useful, according to Kadison.

Although symptoms of SAD resemble those of clinical depression, sufferers do not necessarily exhibit signs of depression. Instead, they may feel lethargic and unmotivated to get out of bed or perform simple daily tasks.

Although the causes of SAD have not been wholly determined, many researchers have postulated that a lack of morning light fails to suppress melatonin.

Students’ daily schedules do not often conform to their biological clocks’ pleas for them to sleep when it begins to grow dark outside.

Some Harvard students, however, haven’t allowed the lack of sunshine to dampen their moods.

“The winter weather hasn’t affected my mood that much,” said Abraham Lin ’10, of Sunnyvale, Calif, “although I have friends back home who wouldn’t be able to survive the cold and snow.”