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.
I’m 6’4" (193cm). I don’t.
I’m not as tall, but that’s my problem too. Now give me a business/first class seat that reclines and I fit in and I’ll sleep no problem!