In my experience sleep depredation is sleep depredation. Being 20 years old doesn't make you immune. Being 50 doesn't make you shrivel up and die. I'd say, for me, I don’t notice much difference between 20 and 50. If anything I'd say it takes slightly longer to recover from commutes now than before. I'd say the same thing about hard exercise. My body can still do the same things, but seems to need a little more recovery time afterwards to get back into hemostasis. Obviously I think there is a lot more difference the older one gets though. There's a reason why pilots are/were forced to retire from 55-65, depending on the time/place.
To a certain point experience can compensate for age, like previous posters alluded to. You learn best practices. You don't get as stressed out. I used to get terribly stressed out about commutting. To the point I'm sure it had a bad physical effect on me. I still don't enjoy commutting, but I've learned to not stress out about what I can't control. If I don't make it it's not the end of the world. Airlines should really plan for that eventuality. If they really wanted me there they would positive space me. You learn to let go.