Seasonal affective disorder (SAD) is a type of depression that comes and goes with the seasons. It usually starts in the late fall and early winter and goes away during the spring and summer. Some people do have episodes of depression that start in the spring or summer, but that is a lot less common. Symptoms of SAD may include
- Gloomy outlook
- Feeling hopeless, worthless, and irritable
- Loss of interest or pleasure in activities you used to enjoy
- Low energy
- Difficulty sleeping or oversleeping
- Carbohydrate cravings and weight gain
- Thoughts of death or suicide
SAD is more common in women, young people, and those who live far from the equator. You are also more likely to have SAD if you or your family members have depression.
The exact causes of SAD are unknown. Researchers have found that people with SAD may have an imbalance of serotonin, a brain chemical that affects your mood. Their bodies also make too much melatonin, a hormone that regulates sleep, and not enough vitamin D.
The main treatment for SAD is light therapy. The idea behind light therapy is to replace the sunshine that you miss during the fall and winter months. You sit in front of a light therapy box every morning to get daily exposure to bright, artificial light. But some people with SAD do not respond to light therapy alone. Antidepressant medicines and talk therapy can reduce SAD symptoms, either alone or combined with light therapy.
NIH: National Institute of Mental Health
- Light Therapy Boxes for Seasonal Affective Disorder (Mayo Foundation for Medical Education and Research) Also in Spanish
- Psychotherapies (National Institute of Mental Health)
- Seasonal Affective Disorder (National Institute of Mental Health) Also in Spanish
- Seasonal Affective Disorder (SAD) (Mayo Foundation for Medical Education and Research) Also in Spanish
- Seasonal Affective Disorder Sufferers Have More Than Just Winter Blues (American Psychological Association)
- Seasonal Affective Disorder: For Teens (Nemours Foundation) Also in Spanish
- Seasonal affective disorder: MedlinePlus Genetics (National Library of Medicine)
- ClinicalTrials.gov: Seasonal Affective Disorder (National Institutes of Health)
Journal Articles References and abstracts from MEDLINE/PubMed (National Library of Medicine)
- Article: Melanopsin-driven pupil response in summer and winter in unipolar seasonal affective...
- Article: Childhood maltreatment reports in adult seasonal affective disorder: Associations with sleep...
- Article: Bipolar II disorder has the highest prevalence of seasonal affective disorder...
- Seasonal Affective Disorder -- see more articles