Seasonal Affective Disorder (SAD)

Seasonal Affective Disorder (SAD)—Diagnosis and Treatment

Seasonal Affective Disorder (SAD)—Diagnosis and Treatment

Learn about the causes, symptoms, and treatment options for seasonal affective disorder (SAD).

Table of Contents

What Is Seasonal Affective Disorder?

Seasonal affective disorder, also referred to as SAD, seasonal depression, or winter depression, is a form of depression. In the Diagnostic Manual of Mental Disorders, Fifth Edition (DSM-5), seasonal affective disorder is identified as major depressive disorder with a seasonal pattern.

People with SAD experience mood changes and symptoms similar to depression. The symptoms usually occur during the fall and winter months when there is less sunlight, then improve with the arrival of spring. The most difficult months for this disorder in the United States tend to be January and February. While it is much less common, some people experience seasonal affective disorder in the summer.

The Effects of Daylight

SAD is more than just “winter blues.” This disorder is linked to a biochemical imbalance in the brain prompted by shorter daylight hours and less sunlight in winter. The symptoms can be distressing and overwhelming, interfering with daily functioning. Fortunately, treatment options are available to lessen the symptoms.

As seasons change, people experience a shift in their internal biological clock or a circadian rhythm that can cause them to be out of step with their daily schedule. SAD is more common in people living far from the equator, where there are fewer daylight hours in the winter.1

SAD Statistics

Below are some seasonal affective disorder statistics:2


  • It is estimated to affect eleven million Americans every year
  • It is much more common in women than in men
  • Typically starts around the age of twenty
  • It usually lasts 40% of the year
  • 6% have required hospitalization
  • 55% of people have family members with a depression issue
  • 34% have family members with alcohol abuse
  • It is more common in the northern states

Seasonal Affective Disorder (SAD) Types

There are two main types of seasonal affective disorder—fall and winter SAD. While spring and summer SAD exist, these types of the disorder are far less common.

Fall and Winter SAD

SAD begins and ends at about the same time every year. Most commonly, seasonal affective disorder symptoms start in the fall and continue into the winter months, draining energy and causing irritability. These symptoms often resolve during the spring and summer months.

Spring and Summer SAD

Less often, SAD causes depression in the spring or early summer and resolves during the fall or winter months, and this is known as spring and summer seasonal affective disorder.3

Seasonal Affective Disorder (SAD) Causes and Risk Factors

Seasonal affective disorder is a fairly complex disorder with several possible causes and risk factors. It is important to know the relevant causes and risk factors in order to be an ally to others and recognize the symptoms to ensure support.


While the exact cause of seasonal affective disorder is unknown, there are a series of possible causes:

Lack of Sunlight

It is believed a decrease in exposure to sunlight plays a major role in developing seasonal affective disorder. It may be linked to the body’s internal clock, which controls temperature and hormone production. In addition, the nerve centers in the brain that control daily rhythms and moods are stimulated by the amount of light entering the eyes.

Melatonin Levels

SAD may also be related to melatonin levels in the body, a hormone secreted by the pineal gland that produces melatonin during the night, causing tiredness. In the morning, the sun’s bright light causes the gland to stop producing melatonin. Thus, on dull winter days, not enough light is received to trigger this waking-up process, causing continued production of melatonin during the day.


Serotonin, an important brain chemical that affects mood, may also play a role in SAD. Similar to melatonin being produced during the night, the production of serotonin may be increased during the day with the help of sunlight. Therefore, less sunlight reduces the amount of serotonin produced in the body, causing symptoms of depression.

Seasonal Affective Disorder (SAD) Risk Factors

There are a few risk factors associated with seasonal affective disorder.


Geography seems to play a role. SAD is more common among people who live in northern climates or move from sunny, southern climates to a more northern climate. 

History of Depression

If someone has a history of depression, they may be more susceptible to developing this disorder. In addition, a family history of depression or other psychological conditions increases the risk of SAD.

Signs and Symptoms of Seasonal Affective Disorder (SAD)

Seasonal affective disorder symptoms include:5


  • Sadness
  • Gloomy outlook
  • Feeling hopeless, worthless, and irritable
  • Loss of interest or pleasure in activities one used to enjoy
  • Low energy
  • Difficulty sleeping or oversleeping
  • Carbohydrate cravings and weight gain
  • Thoughts of death or suicide

How Is Seasonal Affective Disorder (SAD) Diagnosed?

If SAD is suspected, a complete evaluation using current DSM-5 depression criteria is needed. Note that there is no specific seasonal affective disorder test.

Several instruments can be used to screen for depression and determine its severity instead of, or in addition to, a clinical interview. Two of the most commonly used tools are the Beck Depression Inventory and the Hamilton Rating Scale for Depression.

Evaluation for comorbid psychological problems is essential. Because there may be a seasonal component in bipolar or cyclothymic disorders, it is crucial to determine the presence of a cyclical pathology and symptoms of major depressive disorder—treatment considerations for these conditions vary.6

seasonal affective disorder treatment 

Seasonal Affective Disorder Treatment

SAD is a depressive condition and is mainly treated the same way as depression, except for one or additional therapies that might assist. 


Psychotherapy is the treatment of mental disorders by psychological methods rather than medical means. Since SAD falls under general depressive disorders, psychotherapy is often used to treat it. 


Patients might be offered an antidepressant, either on its own or with talking therapy. This will most commonly be a selective serotonin reuptake inhibitor (SSRI).

Light Therapy

Some people say they find it helpful to use a lightbox—a device that gives off intense white or blue light—or a lamp or an alarm clock that simulates dawn. Nonetheless, more research needs to be done to establish whether it is effective and why some people find it helpful and others don’t.7

Treatment for Seasonal Affective Disorder (SAD) at J. Flowers Health Institute

J. Flowers Health Institute provides evaluations and wellness programs for various disorders and conditions, including seasonal affective disorder. Our clinical approach to health is comprehensive, proactive, integrative, and focused on resolving the root cause of health issues to optimize one’s quality of life.

To find out more about seasonal affective disorder and how we can help you or a loved one, please contact us today.