When my body is heavily fighting off a nasty virus, my rapid cycling bipolar symptoms sometimes come back. Yesterday I went from being fine, to incredibly anxious and depressed, to pissed off, to suicidal, straight to laughing and joking, then immediately back to depressed and suicidal again, then back again to laughing and joking, then finally back to being fine. At that point I thought "screw it, I better go to sleep now and avoid my mind being awake." All of that happened in about an hour and a half total.