Sorry, not having the best of days.
I am bipolar but not an expert by any means. As far as I know the frequency and duration of mood swings varies form person to person and depends on the type of bipolar. Bipolar II have mood swings that last at least 4 days (Hypomania), Bipolar I have longer manic phases lasting at least 1 week. Frequency varies. In my own case, I have recently been diagnosed as Bipolar and as yet they haven't specified which. My depressive stages go on for months and my highs tend to go on for a couple of months, starting as a happy high, I can do anything and turn into some sort of superwoman, I do get grandious ideas and spend loads of money at this stage to feed my grandiosity, then it starts to change, the spending becomes pointless, I take on too much, my mind races everything gets too much, I can't concentrate on anything and my life spirals downwards into depression and then the cycle starts again. I know some people have periods of normality in-between phases. I am by no means typical and others experience different things. Theres loads on the internet about it just google Bipolar.
My trigger is stress, but again this varies.
Meant to say I get the thoughts as well at moments of complete and utter desperation but am also unlikely to act.
Hope this has helped