is at the end of the night you are getting pretty sleepy, you've had some beers and so forth, so you think it's time to go home but home's at least 30 to 60 mins away.

So you crawl onto a bus or tube and smack yourself occasionally to make sure you fall asleep and wake up in South London or somewhere equally terrible, like Milton Keynes and then finally you get to your stop...and there's that 5-10 minute walk home that's just enough to wake you up so you spend another hour at home wishing you'd stayed out and had fun in the pub until you can finally drop off to have too little sleep.