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Diseases & Conditions A - Z
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Seasonal Affective Disorder

What Is Seasonal Affective Disorder?

Seasonal affective disorder (SAD) is a psychological condition that results in depression. It is normally provoked by seasonal change. People typically experience the condition in winter (PubMed, 2013). The condition most often occurs in women and in adolescents and young adults (NAMI, 2012).

What Causes of Seasonal Affective Disorder?

The exact cause of SAD is unknown. Contributing factors can vary from person to person. However, people who live in parts of the country that have long winter nights (due to higher latitudes) and less sunlight are more likely to experience the condition. For example, SAD is more common in Canada and Alaska than in sunnier Florida (NAMI, 2012).

Light is thought to influence SAD. One theory is that decreased sunlight exposure affects the natural biological clock that regulates hormones, sleep, and moods. Another theory is that light-dependent brain chemicals are more greatly affected in those with SAD.

People whose family members have a history of psychological conditions are also at greater risk for SAD.

What Are the Symptoms of Seasonal Affective Disorder?

While SAD affects people differently, symptoms most commonly begin is in October or November and end in March or April. However, it is possible to experience symptoms before or after this time.

Generally speaking, there are two types of SAD: wintertime and summertime.

Symptoms of wintertime SAD include:

  • daytime fatigue
  • difficulty concentrating
  • feelings of hopelessness
  • increased irritability
  • lack of interest in social activities
  • lethargy
  • reduced sexual interest
  • unhappiness 
  • weight gain

Symptoms of summertime SAD include:

  • agitation
  • difficulty sleeping
  • increased restlessness
  • lack of appetite
  • weight loss

In severe instances, people with SAD can experience suicidal thoughts.

How Is Seasonal Affective Disorder Diagnosed?

The symptoms of SAD can mirror several other conditions. These include:

  • bipolar disorder
  • hypothyroidism
  • mononucleosis

A physician may recommend several tests to rule out these conditions before they can diagnose SAD, such as thyroid hormone testing with a simple blood test.

A physician or psychiatrist will ask you several questions about your symptoms and when you first noticed them. People with SAD tend to experience symptoms every year. It is not typically related to an emotional event, such as a relationship break-up.

How Is Seasonal Affective Disorder Treated?

Both forms of SAD can be treated with counseling and therapy. Another treatment for wintertime SAD is light therapy, in which a specialized light box or visor is used for at least 30 minutes each day to replicate natural light.

Another option is a “dawn simulator,” which uses a timer-activated light to mimic the sunrise. This helps to stimulate the body’s clock.

Light therapy should be used only under a physician’s supervision and on approved devices. Other light-emitting sources, such as tanning beds, are not safe for use.

Healthy lifestyle habits can also help minimize SAD symptoms. These can include:

  • healthy diet with lean protein, fruits, and vegetables
  • exercise
  • regular sleep

Some patients benefit from medications such as antidepressants. These include fluoxetine (Prozac) and bupropion (Wellbutrin).

When Should I Seek Medical Help?

If you experience symptoms associated with SAD, see a physician, counselor, or psychiatrist.

If you have thoughts of wanting to harm yourself or others, or feel that life is no longer worth living, seek immediate medical attention or call the National Suicide Prevention Lifeline at 1-800-273-TALK (8255) for more information.

Content licensed from:

Written by: Erica Roth
Published on: Aug 15, 2012
Medically reviewed on: May 12, 2014: George Krucik, MD, MBA

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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