Seasonal Affective Disorder (SAD) is a type of depression that occurs at certain times of the year, typically in the fall and winter months when daylight hours are shorter. Symptoms may include feelings of sadness, lethargy, and changes in sleep and appetite. The lack of sunlight is believed to disrupt the body's internal clock and affect serotonin levels, which can lead to these depressive symptoms. Treatment options for SAD often include light therapy, psychotherapy, and medication. Many individuals find that exposure to bright light can help alleviate symptoms and improve their mood during the darker months of the year.