Good news: if you maintain your exercise regimen - especially your resistance/weight training - you can maintain the ability to sleep 8 or 9 or 10 hours in a night.
the wife doesn't sleep heavily so she wakes earlier and just leaves me alone :-P
School days they, of course, refuse to get out of bed.
She started doing it on her own when she was 4, but it really started to mesh when I realized what she was doing and set it up for her to eat breakfast without my help (set out a cup and bowl/plate, put juice/milk into a smaller container and move it to the bottom shelf of the fridge, set out muffins or cereal or whatever she's into at the time, etc).
She also sleeps like a rock, so my night-owl habits don't wake her. It's an absolutely amazing routine and I'm terrified of when she grows out of it.