What is seasonal affective disorder (SAD)?
This Q&A explains seasonal affective disorder, its symptoms, causes, and treatment options.
Seasonal affective disorder (SAD) is a type of depression that occurs at specific times of the year, most commonly during the fall and winter months when daylight hours are shorter. While many people experience mild mood changes in response to seasonal shifts, SAD involves more severe symptoms that interfere with daily functioning.
The primary cause of SAD is thought to be reduced exposure to natural sunlight, which disrupts the body’s circadian rhythms and affects the production of serotonin and melatonin—chemicals that regulate mood and sleep. This imbalance can lead to persistent sadness, fatigue, and difficulties with concentration.
Symptoms of SAD often mirror those of major depression and may include feelings of hopelessness, low energy, changes in appetite (often cravings for carbohydrates), social withdrawal, and loss of interest in previously enjoyable activities. For some individuals, SAD may also cause sleep disturbances, either in the form of excessive sleeping or insomnia.
Treatment for SAD typically involves light therapy, which exposes individuals to bright artificial light that mimics natural sunlight. This therapy has been shown to improve mood and regulate sleep patterns in many cases. In addition, psychotherapy, especially cognitive-behavioral therapy (CBT), helps individuals identify and change negative thought patterns associated with depression. Antidepressant medications may also be prescribed in moderate to severe cases.
Lifestyle changes can complement treatment. Spending more time outdoors during daylight, exercising regularly, and maintaining a consistent sleep schedule all support mental well-being during the winter months. Engaging in social activities, even when energy levels are low, can also counteract feelings of isolation.
It is important to distinguish SAD from ordinary “winter blues.” While occasional low moods during colder months are common, SAD involves more persistent and debilitating symptoms. Seeking professional help ensures proper diagnosis and effective treatment.
With the right support and strategies, individuals with SAD can manage symptoms effectively and maintain quality of life throughout the year.