Unbroken, untroubled sleep is a decadent luxury you will never experience ever again. Its up there on the wish list, just above the lottery win.
You will feel irrationally guilty about everything constantly. Spend ten hours trawling every shop you can think of, trying to find a stuffed giraffe because its on the Christmas wish list, only to discover said child wanted an actual, live giraffe? Get in the shit parent bin.
Never, ever, EVER assume because they have gone quiet, everything is OK. This is an emergency situation. If you do not investigate IMMEDIATELY, there will be an incident of epic, cataclysmic proportions. Having fell foul of this rule in the past myself, I have enjoyed wax blocking my bathroom sink, the dog painted in tomato ketchup, eggs and SMA baby milk, a knock at the door from across the road because my child was plastered to the window naked and a child stuck on top of a wardrobe.
Despite all this, they become your whole world. The love you feel towards them is overwhelming.