I'll be honest, the way I worked changed after age 30. I can't do all-nighters anymore, let alone consecutive ones that I could do when in univeristy, and really, up to age 30 or so.
And then I had a kid. I now know why babies are a young person's game. You're not as much as a zombie with the lack of sleep when you are younger.
A friend of mine had a baby at 38, and her prenatal group were all under 25s. A few days after birth, they were all getting together and looking chipper and rested. I had to go and help my friend get sorted to go for coffee. She was a disaster.
I remember feeling like that disaster.
When I look at younger women having babies, they are so relaxed. They sleep with the baby and it doesn't affect their energy levels (and this is with TERRIBLE diets). THey look all kinds of fresh and chipper and not at all tired or haggard. And, it could be because -- unlike my friend and I -- they had a lot of help from family/friends, or it could be just that they were younger.
I was exhausted the first year with DS. Absolutely wrecked, and often looked like a train wreck as well. Looked aged, too.
And hten once I was getting more sleep (like today -- since the kid sleeps well for about 12 hrs), i started to look normal and younger again.