About .5-2% of the population suffers from bipolar disorder.

Men and women are equally affected (unlike unipolar depression, which affects women twice as much).

First degree relatives are 24 times more likely to develop bipolar disorder and depression.

The exact cause is unknown, but it appears to be a dysregulation of our normal circadian rhythm, as well as an extreme oscillation of the normal variation in our appetites for new experiences, sex, or sleep.