Now DP has sneaked off to join her and is also having a nap!!!

Ah well, gives me more time to hatch plans for world domination.

Actually, I think you're bang on the money about going to sleep amidst the noise. Seems that if she has seen the builders working in that room, said hello to them, done a few high fives then she knows what's what and is happy to go to sleep despite the noise. Maybe I should tape record them and when they've gone replay the building noises which will mask my dishwasher-unloading and flushing of toilets.