The shorter, colder days are leaving some people feeling down.

Doctors estimate as much as 20% of the population will experience Seasonal Affective Disorder this winter.

The form of depression happens more often in women, teens, and older adults.

Symptoms are very similar to depression including an increased appetite, poor sleep habits, and moodiness.

A local doctor says it's nothing to be taken lightly. "Just like depression, it's not something that we want to mess around with because it can be something that can cause people to really change their moods and their minds as what we might do if we're mentally healthy," said Gundersen Lutheran Wellness Specialist Christie Harris.

Harris recommends getting adequate sleep, maintaining a healthy diet, and exercising.