Professionals look for the following key symptoms when deciding if you are depressed.
Depressed or irritable mood most of the day, nearly every day
Loss of interest or pleasure
Changes in weight or appetite
Sleep problems
Agitation
Tiredness and loss of energy
Feeling guilty or worthless
Difficulty in concentrating or making decisions
Thoughts of death or suicide
You are likely to receive a diagnosis of depression if you experience at least five of these symptoms over a two-week period. However, the most important signs are depressed mood most of the day, nearly every day, or a loss of interest or pleasure in things you previously enjoyed. People have different patterns of depression; for example some people are severely depressed for a relatively short time while others have milder depression over a number of years. Even if the depression seems mild it is still important to identify it, as it can have a big impact on your life and you are more likely to face serious depression later on in life.
