For some reason I sleep much better in rear facing seats. It could be because of the angle of attack, which results in the head being on a level below the feet.

best sleeps on overnight flights in the following order:

64A or 62A/K on the UD. Often 90% of the flight knocked out in a good sleep.
Rear facing bulkhead seats on the main CW deck of 747 and 777 (extra legroom).
F
Other CW seats.