babygro sleeping bag
 

how bizarre, but it look a lot more comfortable that a mummy bag

Lippi Selk Bag

I had something similar years ago (oh no I sounds like one of those "I had it before you" people). I think it was Norwegian or Finnish Army issue, and it was great for getting coffee, breakfast in you in the morning without having to expose any parts to the cold. The downside was the packsize, obviously all that extra material takes up more space, but it might be different with this new product.

Also it's great for when the power goes off at home and the heating's out.