As the days grow shorter and the skies turn gray, do you feel more tired, unmotivated, or withdrawn? You’re not alone. Many people experience seasonal mood changes, sometimes severe enough to disrupt daily life. If this sounds familiar, you may be experiencing Seasonal Affective Disorder (SAD) — a form of depression linked to seasonal changes during the fall and winter months, when there is less daylight. In rare cases, people even experience SAD in the spring and summer.