How Common Are the Winter Blues? Winter affects more people than you might think: 10–20% of people experience mild seasonal mood changes often called winter blues . 2–5% of people experience more severe symptoms that meet criteria for Seasonal Affective Disorder (SAD) . SAD is 4 times more common in women , and symptoms typically appear between ages 18–30. People living farther from the equator are significantly more likely to experience seasonal mood dips due to reduced wint