Yep, not everyone can function on a irregular schedule; we are not all wired the same way. When I was in the Military I was a truck driver for this very reason; I could go for 27 hours and not make a mistake. Back then I thought this was normal because I was in with other guys who had the same ability, I only later found out that it's actually a really bad idea to go that long without sleep. I spent a year living with an irregular schedule in the Military, but also later in life, I often worked through the night to get things ready or repaired so people could get back to work the next morning. I would no longer volunteer to work those hours today, employers have a habit of abusing this.