I can almost never get any real sleep or rest in Y. The most I've ever gotten in one nap was about 90 minutes.

In J, I can usually pass out after enough alcohol in my system so long as the bed/seat is flat (VS, BA, NZ, AC)... Almost no real sleep, but can rest on AA, LH. However, the combination of too much alcohol plus altitude usually results in a not fun next day for me.