I wear them at home, usually on days I can't be bothered to get dressed or go out, which is usually after I get in at 9am after an exhausting nite working a gig...
V comfortable, although being size L, they have got the nickname of 'romper suit', although i personally think they resemble (MC) Hammer pants...
I do sleep in them from time to time too.
Most useful they have ever been was after flying into SFO in F, crashing for the nite at a $40 roach motel somewhere down the CA1 highway... you couldnt have paid me to sleep with skin touching that bed !