[S]leep, or the lack of it, is probably the biggest cause of arguments in relationships, well in relationships that involve the shared care of a baby anyway. It's amazing how, based purely on the fact that they are asleep and you are not, it is possible to feel pure hated for another human being. The mere suggestion of a contented sleepy sigh from your partner when you're awake with a baby (born with the inhuman ability to sense a cot mattress approaching) is enough to undo any humanity or decency that you once saw in them. And no doubt the ...