Diagnosing Seasonal Affective Disorder can be tricky. There is no test for it. And since it is related to seasonal patterns it can take a few years of observation to make that connection. But if your symptoms can be traced to the causes of seasonal affective disorder then your treatment can be much more effective.
The first step in diagnosing seasonal affective disorder comes from understanding that the depression, lethargy, or other symptoms of seasonal affective disorder can be related to a seasonal pattern. They may have their onset during winter or summer, or the symptoms may worsen or lighten on a yearly basis. Once you are aware of this possibility you can start observing and documenting what happens and gather all the information your doctor will need to determine if you suffer from seasonal affective disorder.
When it is time to see a doctor for seasonal affective disorder a diagnosis will be based on a detailed medical history concerning your symptoms. Your observations of the affect of the seasons on them will help at this point.
A doctor or other mental health care provider will ask you questions about how you feel, your mood, your interactions with others, and how they change through the seasons. Additional information on how you sleep and how you eat is pertinent. Questions concerning your job, relationships, physical activity and feelings of stress may be asked as well. There are many standardized psychological questionnaires and your doctor may want you to fill out one or more of these.
A doctor will most likely want to perform a physical exam to gauge your overall health. Blood tests as well as imagery tests, such as an MRI, may also be conducted to rule out any other disorder that could be causing your symptoms.
Typical criteria used to diagnose seasonal affective disorder includes:
Experiencing the symptoms of seasonal affective disorder for two or more consecutive years with the same seasonal pattern
You have a cyclical occurrence of symptoms. That is a period of experiencing symptoms followed by a period of not experiencing symptoms, or periods of worsening and lightening of symptoms.
There are no other explanations for your cyclical changes in mood or behavior.
A definitive diagnosis of seasonal affective disorder is difficult. It is considered a subtype of bipolar disorder and shares a host of symptoms with other mental health and physical disorders. However, treatment for seasonal affective disorder may be conducted if a seasonal component to your issues is suspected.