People who are in a depressive state are often sad and pessimistic. They may lose interest in activities they usually like, or become isolated and lonely. Other symptoms include anxiety, hopelessness, changes in sleep, and suicidal thoughts. A depressive episode can last from a few weeks to several months. When bipolar disorder develops at a young age, the first few episodes are usually depressive. Because a manic or hypomanic episode is needed to diagnose bipolar disorder, some people are diagnosed with major depression at first.