Dr. Angelos Halaris of the Loyola University Health System in Maywood, Ill., says SAD is characterized by depression, exhaustion and lack of interest in people and regular activities, and can interfere with a person's ability to function properly.
"The most common type of this mood disorder occurs during the winter months," Halaris says in a statement. "SAD is thought to be related to a chemical imbalance in the brain, brought on by lack of light due to winter's shorter days and typically overcast skies."
Halaris says a tendency to crave sweets is common with SAD. In addition, social relationships are hindered.
"If at all possible, get outside during winter, even if it is overcast," Halaris recommends. "Expose your eyes to natural light for one hour each day. At home, open the drapes and blinds to let in natural light. SAD can be effectively treated with light therapy, antidepressant medication and/or psychotherapy."