I remember being so physically and mentally drained that while breast feeding during the night, I would drift off to sleep and waking up so disorentated that I didn't know if I had just started feeding or finished.

They say in the weeks leading up to the birth of your baby you should get as much rest and sleep as possible, because you don't get very much when baby arrives. This makes no difference. There is nothing worst than not getting enough sleep, and the little sleep you do get is broken.