I've done 40+ hours straight numerous times when I was younger.
Now, 8 hours into a 12 hour shift I'm thinking DAMN!! SCREW THIS!!
And just for the record,
I've never done any drugs OTR.
That era was pretty much past when I got started.
BUTT, almost to a man, all the guys that were old timers when I started DID do them...
and didn't have any compunction about saying so.
And they'd be deeply offended if you called them dopers or such.
That's just how it was.
Of all the 50's n 60's truckers I ever knew, none of them ever hurt anybody or crashed a truck.
Not saying it was right, necessarily,
but it was what it was.
I had one pal who retired with a 4 million mile safe driving award...
and 5 DWI's.
And they were the same bunch that were known as knights of the road.
Suck on that for a while.