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.
It is harder in those crappy economy seats where your knees are up in the back of the seat in front of you lol, I don’t fly first class much, but I have a frequent flyer level that usually allows me to get preferred seats with more legroom. But planes knock me out anyway… Like a baby… Even if I am in a tight seat haha. I’m 6 ft tall, not super tall, but tall enough to get that sardine feeling in some of those seats… Then even tho I get the window, the guy next to me many times is some huge mofo who hangs over into my space lol