Winter is in full swing across the country and it's impacting many people's travel plans, but winter is also affecting something else, our moods. Experts at the Mayo clinic say seasonal affective disorder usually occurs during the cold, dark months of winter. Symptoms include sleepiness, social withdrawal and difficulty concentrating. Researchers say taking a walk outside or using light therapy can be enough to help people with the condition. However, professional help may be needed for some people.