Seasonal affective disorder (SAD) is a type of depression. It is linked with seasonal changes in light. For most, SAD occurs in late fall and lasts into spring. For others, it starts in the summer and ends in the fall. SAD can cause problems with normal daily functions.
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The exact causes of SAD are not clear. It may be due to:
SAD is more common in women and young adults. People who live in northern latitudes also have a higher risk of SAD.
Those with depression or bipolar disorder may have a seasonal worsening of depression.
Symptoms of SAD usually appear during winter months. Symptoms tend to disappear in spring and summer. SAD may cause:
The doctor will ask about your symptoms and health history. A physical and mental health exam will be done.
A diagnosis of SAD is based on symptoms and:
The goal of treatment is to ease symptoms. Options are:
Sometimes supplements are used to improve mood. They may include vitamin D and tryptophan. Melatonin may be taken for sleep problems.
If SAD happens each year, the doctor may prescribe bupropion or light therapy to prevent it.
Depression and Bipolar Support Alliance
Mental Health America
Canadian Mental Health Association
Canadian Psychiatric Association
Galima SV, Vogel SR, et al. Seasonal affective disorder: common questions and answers. Am Fam Physician. 2020;102(11):668-672.
Seasonal affective disorder. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/seasonal-affective-disorder Accessed March 10, 2021.
Seasonal affective disorder. Family Doctor—American Academy of Family Physicians website. Available at: https://familydoctor.org/condition/seasonal-affective-disorder. Accessed March 10, 2021.
7/20/06 DynaMed Systematic Literature Surveillance. https://www.dynamed.com/condition/seasonal-affective-disorder : Lam RW, Levitt AJ, et al. The Can-SAD study: a randomized controlled trial of the effectiveness of light therapy and fluoxetine in patients with winter seasonal affective disorder. Am J Psychiatry. 2006;163(5):805-812.
2/16/2016 DynaMed Systematic Literature Surveillance. https://www.dynamed.com/condition/seasonal-affective-disorder : Rohan KJ, Mahon JN, et al. Randomized trial of cognitive-behavioral therapy versus light therapy for seasonal affective disorder: acute outcomes. Am J Psychiatry. 2015 Sep 1;172(9):862-869.
Last reviewed January 2021 by
EBSCO Medical Review Board
Adrian Preda, MD
Last Updated: 03/10/2021