I'm Getting Old

How do I know I'm getting old?

My brother, who I think is only doing it because he has no idea what he's getting himself into, is taking my kids to Disneyland tomorrow.

So of course, although they're supposed to be in bed, they're doing that insane-giddy-I'm-going-to-Disneyland-and-won't-go-to-sleep thing we all did when we were going to go to Disneyland.

I've discovered that being the slightly peeved parent who is the killjoy who tells them to go to bed and stop being so excited is just as much a rite of passage as being the excited kid who won't go to sleep.

This must be a significant parent moment, equivalent to unearthing a monolith in an Arthur C Clarke story. I wonder what it signals?