Insomnia is common in bipolar in general. The biggest danger with that is that insomnia can trigger a major spike in mania. Energy levels, btw, can be linked to mood swings. If you go through a long depressive phase, your body is going to want to balance that with the consistent high energy of a matching manic phase. That's one of the ways bipolar causes insomnia. There's also the racing thoughts, as well...but now I'm splitting hairs ;P