I can fall asleep almost anywhere. I routinely fall asleep in the break room at work. Once, I was helping a friend fix his car, and I fell asleep on his garage floor when he went inside to get water.
But in a hot metal tube tearing through the sky, with my neck all kinked? Get out of here, man.
Ambien. Anyway, I have a Zzzband “pillow” that’s essentially a large eye mask that has straps to strap your head to the headrest of your seat, great “travel pillow” I’ve ever used and I fly about 40 times a year.