I've learnt to do as much as I can during the day, then I crash on the lounge once DD is in bed, around 7.30 - 8pm.
I don't deal well with little sleep so I have my wind down in front of the tv then crash in bed early. When I wasn't pregnant I tended to stay up and sew or read but at the moment I'm just too tired to concentrate by that end of the day!