Depression (also called major depressive disorder or clinical depression) is a common but serious mood disorder. It causes severe symptoms that affect how you feel, think, and handle daily activities, such as sleeping, eating, or working. To be diagnosed with depression, the symptoms must be present for at least two weeks. There are different types of depression, some of which develop due to specific circumstances.
- Major depression, which includes symptoms of depression most of the time for at least 2 weeks that typically interfere with one’s ability to work, sleep, study, and eat.
- Persistent depressive disorder (also called dysthymia), which often includes less severe symptoms of depression that last much longer, typically for at least 2 years.
- Perinatal depression, which occurs when a woman experiences major depression during pregnancy or after delivery (postpartum depression).
- Seasonal affective disorder, which comes and goes with the seasons, typically starting in late fall and early winter and going away during spring and summer.
- Depression with symptoms of psychosis, which is a severe form of depression where a person experiences psychosis symptoms, such as delusions (disturbing, false fixed beliefs) or hallucinations (hearing or seeing things that others do not see or hear).
Individuals with bipolar disorder (formerly called manic depression or manic-depressive illness) also experience depressive episodes, in which they feel sad, indifferent, or hopeless, combined with a very low activity level. But a person with bipolar disorder also experiences manic episodes, or unusually elevated moods in which the individual might feel very happy, irritable, or “up,” with a marked increase in activity level.
Examples of other types of depressive disorders newly added to the diagnostic classification of Diagnostic and Statistical Manual of Mental Disorders (DSM-5) include disruptive mood dysregulation disorder (diagnosed in children and adolescents) and premenstrual dysphoric disorder (PMDD).
Signs and Symptoms
If you have been experiencing some of the following signs and symptoms most of the day, nearly every day, for at least two weeks, you may be suffering from depression:
- Persistent sad, anxious, or “empty” mood
- Feelings of hopelessness, or pessimism
- Feelings of irritability, frustration, or restlessness
- Feelings of guilt, worthlessness, or helplessness
- Loss of interest or pleasure in hobbies and activities
- Decreased energy, fatigue, or feeling "slowed down"
- Difficulty concentrating, remembering, or making decisions
- Difficulty sleeping, early morning awakening, or oversleeping
- Changes in appetite or unplanned weight changes
- Thoughts of death or suicide, or suicide attempts
- Aches or pains, headaches, cramps, or digestive problems without a clear physical cause that do not ease even with treatment
- Suicide attempts or thoughts of death or suicide
Not everyone who is depressed experiences every symptom. Some people experience only a few symptoms while others may experience many. Several persistent symptoms in addition to low mood are required for a diagnosis of major depression, but people with only a few – but distressing – symptoms may benefit from treatment as well. The severity and frequency of symptoms and how long they last will vary depending on the individual and his or her particular illness. Symptoms may also vary depending on the stage of the illness.