Staying up late is different when you're over 40, but it still has a bit of that tinge of "pushing boundaries" that it did previously. One major difference however is what my old body seems to consider "late".
When I was younger, I used to go to lock-in events at the local laser tag arena, and run around all night long until it was 6AM and they opened the doors and let us out. Heading home and going to bed at 7AM was a unique experience for me then, and it sounds totally exhausting to current me. But I know that I had fun, and that was the important part!
These days, if it gets past 10PM I'm shocked at my bravery at staying up so late, being so transgressive with my time. I'm usually the one reminding my partner that it's time to go to bed, but on the rare occasions (like tonight) where she's out of town and I'm alone with no resposibilities, I can be "bad" and stay up late reading and apparently writing phlogs.
The clock just ticked over to July 5th while I was contemplating what to write, but I'm going to keep the date as July 4th just for fun. :)