Seasonal Affective Disorder

(SAD)

by Amy Scholten, MPH

Definition

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.

Brain—Psychological Organ

SAD may be caused by fluctuations in hormones and brain chemicals.

Causes

The exact causes of SAD are not clear. It may be due to:

Changes in sunlight—which affects hormones and brain chemicals
Changes in melatonin levels—a hormone that plays a role in sleep and mood
Changes in serotonin levels—a hormone that controls mood

Risk Factors

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

Symptoms of SAD usually appear during winter months. Symptoms tend to disappear in spring and summer. SAD may cause:

Low, sad, or irritable feelings
Tiredness
Sleeping too much or insomnia
Social withdrawal
Problems focusing
Reduced sexual desire
Overeating and craving sweet or starchy foods
Weight gain

Diagnosis

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:

If they have occurred for at least 2 years
Other major depression has not occurred during the same time
Symptoms are gone during summer

Treatment

The goal of treatment is to ease symptoms. Options are:

Light therapy—sitting near an ultra-bright light for a certain time each day
Antidepressants—to improve mood
Spending time outdoors—to get more sunlight
Counseling, such as cognitive-to behavior therapy —to help with coping

Sometimes supplements are used to improve mood. They may include vitamin D and tryptophan. Melatonin may be taken for sleep problems.

Prevention

If SAD happens each year, the doctor may prescribe bupropion or light therapy to prevent it.

RESOURCES:

Depression and Bipolar Support Alliance
http://www.dbsalliance.org

Mental Health America
http://www.mentalhealthamerica.net

CANADIAN RESOURCES:

Canadian Mental Health Association
https://cmha.ca

Canadian Psychiatric Association
http://www.cpa-apc.org

References:

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

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