According to the American Psychiatric Association, people are clinically depressed and should seek professional help if they exhibit four or more of the following symptoms continually or most of the time for more than two weeks.

• Noticeable change in sleeping patterns.
  

• Inability to concentrate or think, indecisiveness.
  

• Noticeable change of appetite, with either weight gain or significant weight loss not attributable to dieting.
  

• Recurring thoughts of death or suicide, wishing to die, or attempting suicide. (Note: People suffering this symptom should receive treatment immediately!)
  

• Melancholia—overwhelming feelings of sadness and grief—accompanied by waking at least two hours earlier than normal in the morning, feeling more depressed in the morning, and moving significantly more slowly.
  

• Loss of energy or fatigue.
  

• Feelings of worthlessness.
  

• Persistent feelings of hopelessness.
  

• Feelings of inappropriate guilt.
  

• Loss of interest and pleasure in activities formerly enjoyed.
  

• Physical symptoms, such as headaches or stomachaches.
  

• Disturbed thinking, a symptom developed by some severely depressed persons. For example, severely depressed people sometimes have beliefs not based in reality about physical disease, sinfulness or poverty.