Tests and diagnosis

By Mayo Clinic Staff

To help diagnose seasonal affective disorder, your doctor or mental health provider may do a thorough evaluation, which generally includes:

  • Physical exam. Your doctor may do a physical exam and ask in-depth questions about your health. In some cases, depression may be linked to an underlying physical health problem.
  • Lab tests. For example, your doctor may do a blood test called a complete blood count (CBC) or test your thyroid to make sure it's functioning properly.
  • Psychological evaluation. To check for signs of depression, your doctor or mental health provider asks about your symptoms, thoughts, feelings and behavior patterns. Your doctor may have you fill out a questionnaire to help answer these questions.

Seasonal affective disorder is considered a subtype of major depression or bipolar disorder. Even with a thorough evaluation, it can sometimes be difficult for your doctor or mental health provider to diagnose SAD because other types of depression or other mental health conditions can cause similar symptoms.

Many mental health professionals use the criteria in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), published by the American Psychiatric Association, to diagnose mental conditions. This manual is also used by insurance companies to reimburse for treatment.

The DSM-5 criteria for diagnosing depression with a seasonal pattern includes having these experiences for at least the last two years:

  • Depression that begins during a specific season every year
  • Depression that ends during a specific season every year
  • No episodes of depression during the season in which you experience a normal mood
  • Many more seasons of depression than seasons without depression over the lifetime of your illness
Sep. 12, 2014

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