Seasonal Affective Disorder (SAD) is a type of depression that occurs at specific times of the year, most commonly in the fall and winter months when daylight hours are shorter. Symptoms may include feelings of sadness, fatigue, and changes in sleep and appetite. The lack of sunlight is believed to disrupt the body's internal clock and affect levels of certain neurotransmitters, such as serotonin. Treatment options for SAD often include light therapy, which involves exposure to a special light that mimics natural sunlight. Other approaches may include psychotherapy and medication, depending on the severity of the symptoms. Regular exercise and spending time outdoors can also help alleviate symptoms.