I used to take this flight quite often but eventually got fed up with experiences like jamesreid978 had. I tended to eat in town and leave for the airport as others were heading to bed. While it should have been possible to get 6 hours of sleep I rarely got more than about 3.

In the end I gave up on this flight and took the morning daylight back instead which gets in to London shortly after lunch. It was far more civilised and one didn't feel like garbage after the flight.