I'm not sure if rapid cycling gets worse when left untreated, but my rapid cycling seemed to have started when I started meds. Never used to cycle rapidly before that. (But of course it could all be a coincidence. I don't know.)

My depression tends to last 2-3 weeks; my hypo/manias, 1 week. Then I have some time in between where my mood is stable. I seem to get an episode every 2 months or thereabouts?