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.
1-2mg of Melatonin, remain motionless with eyes closed for ~20 minutes, you’ll be out like a light. Make sure you take a smaller dose - most gummies are 5 or 10 mg, it honestly works better if you subdivide.