NEW YORK (PIX11)- As the winter weather begins to settle in, this time of year can depressing for those with seasonal affective disorder or SAD.

Seasonal affective disorder is a type of depression that’s related to changes in seasons. It usually starts in the fall and continues into the winter months.

Thea Gallagher, a clinical psychologist at NYU Langone, joined PIX11 Morning News on Wednesday to explain the disorder that affects one to three percent of people.

Watch the video player for more.