My Father was really strange. He could lie down just about anywhere and immediately go soundly to sleep. I could never do that.
I have a friend who was a Navy pilot for years and then a
commercial pilot until retirement. He never got into a sleep
pattern. He could sleep and be up on about any schedule as
long as the rest averaged out well. He could do this.
I know a lot of fromer Navy people that will tell you, the Navy will teach you to sleep anywhere, anytime, for any amount of time (10 minutes to 10 hours).
I know it did for me.