In order to be diagnosed with major depression

a person must have experienced at least 5 of the 9 following symptoms:

  1. depressed mood,
  2. lack of interest inmost activities,
  3. weight loss or gain,
  4. difficulty getting to sleep or sleeping more than usual,
  5. agitation,
  6. decreased energy level,
  7. extreme guilt or thoughts of worthlessness,
  8. diminished concentration,
  9. and thoughts of suicide or suicide attempts (American Psychiatric Association [APA], 2000)