I know those sleepless nights! For me it was up with the new guy in my mind, thinking about him sexually and then tenderly (like, "What if he were here right now?" and "What if we fell in love?"), I think this type of sleeplessness is normal with most new successful relationships.
I would just take it slowly, and feel it out. When you feel like you absolutely need to know, just ask the guy about it. Honesty and openness is a huge Poly skill to have, very helpful!
I agree that it is difficult if you are alone all of the time, starting a new poly relationship. It always makes me feel more needy and sometimes that can be difficult to reign in.