Thanks to this article, today I learned that there's a name for the thing I have, "delayed sleep disorder."
I became an entrepreneur at age 22 not because I wanted to change the world, but because I just wasn't able to wake up early enough for a "real job." I figured there had to be a way to make the same amount of money I was making at the time, but keep my own hours. I always tell people I have "vampire hours."
I'm 38 years old now. I typically go to sleep around 4am+ every night and wake up around 11am or noon. I usually don't take meetings before 1pm and have unknowingly designed my life and career around this disorder.
I was also diagnosed with ADHD as a kid, which, according to Wikipedia, is linked to this sleep disorder.