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.
Watch a movie on the in-flight entertainment. I can never finish a movie on a plane. No matter what I do, I fall asleep. If I don’t watch anything, I can’t sleep.