ROCKFORD, Ill. (WTVO) — Seasonal affective disorder can cause people to feel depressed or sad during the winter, and a Rockford doctor gives advice on how to feel better.

“If you have a low Vitamin D blood level, fixing that may have some benefit,” said Dr. Eric Trautmann, of SwedishAmerican Hospital.

Across the stateline area, 2021 has brought freezing temperatures and near constant cloud cover so far. Trautmann says the lack of sun can make it challenging for the human body to get the right amount of Vitamin D, which can lead to seasonal affective disorder.

“Part of the reason people get seasonal affective disorder is because we have shorter days and darker days,” he said. “Feeling sad of blue, loss in pleasure of things you like to do, change in your sleep, change in your appetite, possible weight gain or weight loss [are all symptoms].”

David Rockwell is a local resident who says he is fighting depression by staying positive and trying to enjoy life.

“I go out for a walk, pretty much every day, rain or shine, and I just don’t dwell on the negative things in life,” Rockwell said. “Life’s too short. You’ve got to enjoy life.”

According to a study by Boston University, the seasonal depression impacts roughly 10 million Americans.

Trautmann says the best way to treat the disorder is with bright light therapy.

“The primary treatment, still, is bright light therapy [which] can be very effective and you can buy [devices] that provide bright light [for] half an hour a day,” he said. “It’s usually more effective in the morning than in the evening.”