Seasonal Affective Disorder (SAD)

Dr. Jenni Jacobsen, PhD
Author: Dr. Jenni Jacobsen, PhD Medical Reviewer: Victoria Clarke Last updated:

Seasonal affective disorder (SAD) is a type of depression that occurs only at specific times of the year, usually caused by seasonal changes. SAD is treated with talking therapy, antidepressant medications, and light therapy [1].

What is seasonal affective disorder?

Seasonal affective disorder or ‘seasonal depression’ falls under the category of depressive disorders. SAD is sometimes known as ‘winter depression’ as symptoms tend to be more severe during winter and improve during spring. However, there are some cases, albeit much less common, where SAD symptoms occur in the summer months with improvement in the winter months. [2]

In most cases, individuals with seasonal affective disorder typically experience symptoms similar to mild depression, such as irritability and difficulty concentrating. However, some individuals with seasonal affective disorder can experience suicidal ideation and may require hospitalization. [2]

Symptoms of SAD

Some general seasonal affective disorder symptoms are as follows [3]:

  • Feeling fatigued and lethargic despite getting plenty of sleep.
  • Finding it hard to get up in the morning.
  • Gaining weight as a result of overeating.
  • Losing interest in usual activities.
  • A persistent low mood.
  • Either difficulty in sitting still or extremely slow movements.
  • Having a hard time concentrating or making important decisions.
  • Feeling guilty or worthless.
  • Having thoughts of death or suicide.

Winter vs. Summer SAD

In most cases, seasonal affective disorder occurs during the winter when there is less daylight. However, SAD can also occur at other times of the year.

There is limited research into the seasonal differences of SAD. However, it has been suggested that symptoms may differ between summer and winter cases. In the winter months, individuals may experience excessive sleeping, increased appetite, cravings for carbohydrate-rich foods, and weight gain. On the other hand, summer depression may present with symptoms such as insomnia and decreased appetite [4].

Causes of SAD

Although the exact causes are not well understood, it is generally believed that lack of sunlight leads to symptoms of seasonal affective disorder. During the fall and winter months, people are exposed to less sunlight, which can cause a part of the brain, called the hypothalamus, to stop functioning correctly. This impacts the production of two essential hormones, melatonin and serotonin, which regulate sleep, mood, and appetite [1]

In addition to lack of sunlight, some risk factors may make it more likely for somebody to develop seasonal affective disorder, such as [1]

  • Living in an area with four distinct seasons
  • Living in an area of higher altitude
  • Family history of SAD
  • Historical or current depressive disorders
  • Diagnosis of bipolar disorder
  • Gender – a higher percentage of females are diagnosed with SAD
  • Age – young adults are more likely to be diagnosed with SAD

Diagnosing SAD

Doctors and mental health clinicians diagnose seasonal affective disorder using criteria in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) [5]. The DSM-5 does not explicitly list seasonal affective disorder as a diagnosis. Instead, a person’s condition is diagnosed as ‘major depressive disorder with a seasonal pattern.’ There is also a form of SAD known as ‘reverse SAD,’ typically seen in those with co-morbid bipolar disorder. [2] 

The DSM-5 states that, for a diagnosis to be made, a person must have recurrent depressive episodes, with symptoms appearing at a specific time of year. A person must demonstrate symptoms for at least two consecutive years for a diagnosis, and symptoms must improve after a particular season passes. For instance, when a person experiences depression in the winter, they will have a remission in the spring [2]. A medical or mental health professional will use the DSM-5 criteria in their assessment of SAD, where they will consider the nature, occurrence, and history of the symptoms.

Prevention of SAD

There is no guaranteed way to prevent seasonal affective disorder. Instead, the best way to manage the condition is to identify it early and seek treatment. Maintaining a healthy lifestyle and good well-being can also improve SAD symptoms.

Treatment for SAD

The most common forms of treatment for seasonal affective disorder are talking therapy, medication, and bright light therapy.

Talking Therapy

Talking therapy or counseling can help people to manage symptoms of seasonal depression. A particular form of therapy called CBT (cognitive behavioral therapy) can be effective in treating symptoms of seasonal affective disorder [5]. CBT involves identifying distorted thinking patterns and how these may interact with our feelings and behaviors. CBT works on challenging these thoughts and subsequently improve psychological functioning. 


Antidepressant drugs can be effective in cases of seasonal affective disorder. A class of drugs called selective serotonin reuptake inhibitors (SSRIs) are typically used to treat depressive symptoms. Two specific SSRI medications, Prozac and Zoloft, are beneficial for treating seasonal affective disorder symptoms. Wellbutrin, which belongs to a different class of antidepressant drugs, is specifically used in treating seasonal affective disorder and has the most scientific evidence supporting its use [5].

Bright Light Therapy

Many studies have demonstrated that bright light therapy effectively treats seasonal affective disorder. This treatment modality exposes users to a high illuminating fluorescent bulb. Light therapy lamps can be purchased at major retailers. While the exact procedure can vary based on brand and manufacturer guidelines, the general recommendation is that individuals with seasonal depression expose themselves to bright light for 30 to 60 minutes per day [5].

Self-Care for SAD

Self-care can also help manage SAD. Taking time to care for yourself can improve your mood and make symptoms more manageable.

Some beneficial self-care strategies for seasonal affective disorder include [5]:

  • Establishing a regular sleep schedule: Going to bed at the same time each day and waking up around the same time can help you to get enough sleep to feel refreshed. Prioritizing sleep hygiene can help alleviate some feelings of fatigue that can come with seasonal affective disorder. It’s also important to limit screen time before bed and keep your bedroom cool and dark to promote high-quality sleep. 
  • Make time for exercise: Getting regular exercise throughout the week can boost your mood and make seasonal depression symptoms less intense. You might consider going to the gym to lift weights or attending a group exercise class. If this isn’t an option, at-home workouts can also be effective.
  • Expose yourself to natural sunlight whenever possible: Since lack of sunlight is believed to contribute to seasonal affective disorder, getting some exposure during the winter months can be helpful. Open your blinds first thing in the morning to let in natural light. Even better, bundle up and take a walk outside to expose yourself to sunlight and get some aerobic exercise. If long work hours make it difficult to get someexposure tosunlight, open the curtains in your office, or get some time outside during your lunch break.

Frequently asked questions about SAD

How common is seasonal affective disorder?

According to research, the prevalence of seasonal affective disorder depends upon geographic location. Prevalence ranges from 1.5% to 9% of the population [6]. The condition is more common in young adults, especially women [1].

What is the outlook for people with seasonal affective disorder?

According to medical experts, many people experience a recurrence of seasonal affective disorder symptoms; however, the condition can be managed with proper treatment. If you live with seasonal affective disorder, it’s important to stay compliant with treatment, which can include medication, talking therapy, and light therapy. Staying engaged in treatment can alleviate symptoms.

What is the difference between seasonal affective disorder vs. seasonal depression?

The terms “seasonal affective disorder” and “seasonal depression” are often used interchangeably to refer to symptoms of depression that occur during a specific season of the year. When people talk about seasonal depression, they are typically referring to seasonal affective disorder.

  1. Munir, S., & Abbas, M. (2022, January 9). Seasonal Depressive Disorder.; StatPearls Publishing.
  2. American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders(5th ed.).
  3. – Seasonal Affective Disorder (SAD). (n.d.).
  4. Wehr, T.A., Giesen, H.A., Schulz, P.M., Anderson, J.L., Joseph-Vanderpool, J.R., Kelly, K., Kasper, S., & Rosenthal, N.E. (1991). Contrasts between symptoms of summer depression and winter depression. Journal of Affective Disorders,23(4), 173-183. DOI: 10.1016/0165-0327(91)90098-d
  5. Galima, S.V., Vogel, S.R., & Kowalski, A.W. (2020). Seasonal affective disorder: Common questions and answers. American Family Physician, 102(11), 668-672. Retrieved from
  6. Nussbaumer-Streit, B., Greenblatt, A., Kaminski-Hartenthaler, A., Van Noord, M.G., Forneris, C.A. Morgan, L.C., Gaynes, B.N., Wipplinger, J., Lux, L.J., Winkler, D., & Gartlehner, G. (2019). Melatonin and agomelatine for preventing seasonal affective disorder. Cochrane Database of Systematic Reviews.
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Dr. Jenni Jacobsen, PhD
Author Dr. Jenni Jacobsen, PhD Medical Reviewer, Writer

Dr. Jenni Jacobsen, PhD is a medical reviewer, licensed social worker, and behavioral health consultant, holding a PhD in clinical psychology.

Published: Feb 1st 2023, Last edited: Oct 23rd 2023

Victoria Clarke
Medical Reviewer Victoria Clarke MSc

Victoria Clarke is a medical reviewer and a registered pediatric nurse specializing in child and adolescent mental health.

Content reviewed by a medical professional. Last reviewed: Feb 1st 2023