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Diagnosis and clinical terms

Seasonal depression

Shariq Refai, MD, MBA, board-certified psychiatrist and the reviewer of this article.

Reviewed by Shariq Refai, MD, MBA·Updated March 15, 2026·About 3 minutes

About this term

Quick definition
Major depressive disorder with a seasonal pattern, most often beginning in late fall and resolving in spring.
Full clinical definition
Seasonal depression is not a separate diagnosis. It is a specifier added to major depressive disorder or bipolar disorder when episodes follow a seasonal pattern. In the DSM-5-TR, the specifier requires that depressive episodes show a regular temporal relationship with a particular time of year for at least two consecutive years, full remission also follows a seasonal pattern, and no non-seasonal episodes have occurred in the same period.

The winter-pattern type is the most common. It begins in late fall, deepens through winter, and resolves in spring. A smaller group has a summer pattern, with episodes beginning in late spring and resolving in fall.

Epidemiology
Seasonal patterns of depression are more common at higher latitudes, where winter daylight is shorter. Estimated prevalence in the U.S. ranges from less than 2 percent to about 9 percent depending on latitude and the threshold used. Women are affected more often than men. Median age of first onset is in young adulthood.
What it can feel like
Winter pattern: increased sleep, increased appetite, cravings for carbohydrates, weight gain, and a strong pull to stay indoors. Low motivation. Withdrawal from social contact. People often describe a slow heaviness that arrives with daylight changes in late fall. Summer pattern: reduced sleep, reduced appetite, agitation, and weight loss. Less common but well described.
Why it matters
A seasonal pattern changes the treatment plan. Bright light therapy has strong evidence for winter-pattern depression and is often a first or early option. Knowing the pattern also helps a person and their clinician plan for the next year before the season starts again.
How clinicians assess it
A careful longitudinal history is the central tool. A clinician asks about the timing of past episodes, the pattern of recovery, and the season of any current episode. Other contributors to fatigue and low energy, including thyroid disease, anemia, and obstructive sleep apnea, are usually screened. Bipolar disorder is also considered, especially when episodes are recurrent.
Treatment implications
Bright light therapy, using a 10,000 lux light box for 20 to 30 minutes in the morning, has strong evidence for winter-pattern depression. Most people start to notice changes in one to three weeks. Antidepressants, especially bupropion (which has an FDA indication for prevention of seasonal major depressive episodes) and SSRIs, are also effective. Cognitive behavioral therapy adapted for seasonal patterns (CBT-SAD) has growing evidence. Daily morning light exposure outdoors, a steady wake time, and regular movement support the change.
Related terms
Major depressive disorder. Bipolar depression. Bupropion.
Related articles
Seasonal depression (Types). Treatment.

Sources

  • American Psychiatric Association. DSM-5-TR.
  • Rohan KJ, et al. Outcomes one and two winters following cognitive-behavioral therapy or light therapy for seasonal affective disorder. Am J Psychiatry. 2016.
  • Modell JG, et al. Seasonal affective disorder and its prevention by anticipatory treatment with bupropion XL. Biol Psychiatry. 2005.
  • Lam RW, et al. Canadian Network for Mood and Anxiety Treatments (CANMAT) clinical guidelines: bright light therapy in major depressive disorder. Can J Psychiatry. 2016.

Frequently asked questions

What is seasonal depression?
Seasonal depression, clinically called major depressive disorder with seasonal pattern, is a depressive episode that recurs at the same time each year, most often in fall and winter, with full remission in spring and summer. The pattern must repeat for at least two years to meet criteria.
What are the typical symptoms?
In addition to standard depression symptoms, seasonal depression often includes oversleeping, increased appetite (especially for carbohydrates), weight gain, and a heavy, slowed feeling. Energy is low and motivation drops. The pattern usually begins in late fall as daylight shortens.
Does light therapy actually work?
Yes. Bright light therapy, typically 10,000 lux for 20 to 30 minutes within an hour of waking, has evidence comparable to antidepressants for fall-onset seasonal depression. A standard light box, used on most days through the affected months, is the clinical recommendation.
When should I add medication or therapy?
When light therapy alone is not enough, when symptoms are moderate to severe, or when daily functioning is meaningfully affected, antidepressants (often an SSRI) and cognitive behavioral therapy adapted for seasonal depression (CBT-SAD) both have evidence. A combination is common in clinical practice.
Is summer-pattern seasonal depression a real thing?
Yes, though it is less common than winter pattern. Summer-pattern seasonal depression can include insomnia, agitation, and reduced appetite rather than the oversleeping and overeating of winter pattern. Treatment is more often medication and therapy than light therapy.

Last reviewed March 15, 2026.

Every clinical page on DepressionResource.org is written in plain language, dated, and reviewed by a board-certified psychiatrist against current clinical guidelines. See our editorial standards and medical review process.