Sleeping in J = no problem.
Sleeping in whY = disaster.. Neck,Back,cough pains, Trolley hitting your shoulder or knees every time the cart comes past, people farting, "tapping" the IFE system from behind, crying babies, getting woken up by someone needing to piss, getting woken up by stewardess for 'food' because they are told they have to wake you up... What's not to love about the whole experience. I take a sleeping pill that only gives me 3-4 hours if I'm lucky - the rest of the time I contemplate my existence and wonder how we have managed to turn travel into such an unpleasant experience. Cattle class is a very accurate description.
Happy to hear any suggestions for pillows that do the job and don't cause my neck to feel like death.. I try upgrade as much as I can as well. My trips average 25+ hours of flight time.