It's funny, growing up. There is no magical day when you are suddenly more grown up. Birthdays help reinforce how old we are and perhaps encourage us to act our age. Funny story, sometimes in the evenings it's early, before 8 PM and I feel like I am fighting myself to go to sleep. I am exhausted, but going to sleep before 8 PM seems ridiculous! So like a whining child I find something else to do, at least until 8, then I can go to sleep.
For the record, maybe once a month or so I do actually go to sleep before 8 PM. It first happened about three years ago, and it is more common now.