Before diagnosing you with seasonal affective disorder (SAD), a health professional will ask about your medical history.

Your health professional may order blood tests to check for other conditions, such as hypothyroidism, that could be causing your depression. He or she also may ask you to complete a questionnaire regarding changes in your sleep patterns, social activity, mood, weight, appetite, and energy levels.

The questionnaire may ask the following:

• Do you feel a dramatic reduction in energy when the days get shorter and darker?
• Do you have difficulty waking up in the morning?
• Do you sleep more than you used to or sleep too much?
• Are you eating more than you used to or more than you should?
• Have you gained weight?

Your health professional may also do a mental health assessment, which includes an evaluation of your emotional functioning and your ability to think, reason, and remember (cognitive functioning). The assessment may also include written or verbal tests and lab tests (such as blood and urine tests). During the interview, your health professional will assess your appearance, mood, behavior, thinking, reasoning, memory, and ability to express yourself and may ask about your personal relationships and family history of SAD.