Certainty that an acute episode [of depression] will last only a week, a
month, even a year, would change everything. It would still be a
ghastly ordeal, but the worst thing about it -- the incessant yearning
for death, the compulsion toward suicide -- would drop away. But no, a
limited depression, a depression with hope, is a contradiction. The
experience of convulsive pain, along with the conviction that it will
never end except in death -- that is the definition of a severe
~ George Scialabba
Clinical depression is a mood disorder that causes continuous feelings of sadness and hopelessness, loss of interest and energy, and getting no joy from things that previously gave you joy. Depression affects an individual's thoughts, feelings, and behaviors, and can lead to a number of problems, both physical and emotional. Individuals often report not being able to get started on tasks, losing their motivation, and having trouble with regular daily activities. Another common feeling associated with depression is that life is no longer worth living. There is no single cause for depression.
However, depression can present itself in a number of ways and goes by many names, though the commonality is feeling depressed for weeks or months, not a passing blue mood. Depression is, in essence, an umbrella term for a number of depressive disorders. The most well-known is major depression, the symptoms of which include interference with work, sleep, studying, eating, and enjoying life. A major depressive episode can occur only once, but an individual will often experience several episodes. The second, and only slightly less well-known, is persistent depressive disorder, which is a depressed mood lasting for at least 2 years. During these two years, an individual with persistent depressive disorder might have episodes of major depression as well as periods of less severe symptoms. Other forms of depression are more specific to circumstances, such as psychotic depression (when an individual has severe depression along with a form of psychosis like delusions or hallucinations), postpartum depression (occurring after a woman gives birth), and seasonal affective disorder (having depression during the winter months that lifts during the spring and summer when there is more light). Related to depression is bipolar disorder, an illness whereby an individual experiences both manic and depressive episodes.