Seasonal Affective Disorder (SAD)
Population Health
Seasonal Affective Disorder (SAD)
Seasonal affective disorder, known as SAD, is a form of depression in which mood changes usually occur during the fall and winter months when there is less sunlight, and generally improve in spring. Typical signs of SAD include craving carbohydrates, sleeping more than usual and having little motivation. For people with SAD in the United States, the most difficult months are January and February.
SAD is more than just “winter blues.” The symptoms can be distressing and overwhelming and can interfere with daily functioning. According to the American Psychiatric Association, approximately 5% of adults in the U.S. experience SAD, and it is more common among women than men.1
SAD has been linked to a biochemical imbalance in the brain prompted by shorter daylight hours and less sunlight in winter. As seasons change, people experience a shift in their biological, internal clock or circadian rhythm that can cause them to be out of step with their daily schedule.
Symptoms and Diagnosis
Common symptoms of SAD include fatigue and weight gain associated with overeating and carbohydrate cravings. SAD symptoms can vary from mild to severe and can include many symptoms similar to major depression, such as:1
- Feeling sad or having a depressed mood
- Loss of interest or pleasure in activities once enjoyed
- Changes in appetite; usually eating more, craving carbohydrates
- Change in sleep; usually sleeping too much
- Loss of energy or increased fatigue despite increased sleep hours
- Increase in purposeless physical activity (e.g., inability to sit still, pacing, handwringing) or slowed movements (these actions must be severe enough to be observable to others)
- Feeling worthless or guilty
- Difficulty thinking, concentrating or making decisions
- Thoughts of death or suicide
SAD may begin at any age, but it typically starts when a person is between 18 and 30.
