A disorder associated with episodes of mood swings ranging from depressive lows to manic highs. The exact cause of bipolar disorder isn’t known, but a combination of genetics, environment and altered brain structure and chemistry may play a role. Manic episodes may include symptoms such as high energy, reduced need for sleep and loss of touch with reality. Depressive episodes may include symptoms such as low energy, low motivation and loss of interest in daily activities. Mood episodes last days to months at a time and may also be associated with suicidal thoughts.