Bipolar has 2 phases, a manic phase and a depressive phase. In the manic phase, people often go days without sleeping, and partake in risky behaviors (all sorts... sexually, theft, driving dangerously, etc) because they sort of feel invincible. But then it switches to a depressive phase, and in general this illness is scarier than someone with just depression because the person has such a huge swing from feeling on top of the world to being depressed that they often either use drugs to try to feel the mania again, or can be suicidal because they feel so low. Keeping someone with this medicated is hard too, because the manic phase feels amazing, and they want that more than the level state they're in while properly medicated. So they go off the medicine because they want that mania back so badly.
Just thinking out loud...