My depressive episodes I can say are almost always triggered I can usually associate something with the start. Manic episodes seem to just start and then along the way things trigger me to make it more severe. For example I might see a brochure about hiking, and then my mind is like hiking ah what a great idea. Lets get this stuff here and start hiking here, oh btw you know nothing about hiking oh well it is going to be epic. That is how things pan out for me typically.