I'd think it depends on the level of mania, I've seen my bro be able to live without sleep or minimal during his extreme full blown manic episodes, but when he has not escalated to that point, he'll sleep about 6 to 7 hours. If he has had a before or after dinner nap,consisting of about an hour, then he'll get 5 or less, hours sleep before going to work.
I know too, if one is taking amphetimines/or other form of stimulants and has bipolar disorder, the stimulant effect may be stronger than a non-bipolar person. Even nicotine, from a smoke before bed can interfer with sleep.
I'm not saying these are things you are doing,or are not, but just wanted to add this info.
If you are in an episode or approaching one, check with your pdoc to see if he or she can give you something to minimize the flight till you reach stabilization.
Oh, I forgot to ask, "are you taking a mood stabilizer?"
Most people with bipolar are usually prescribed one or a combo.
Just some thoughts. . .