Ever since I was old enough to read, I've been a night owl. A good book would have me reading until late. The usual refrain around our childhood home at night was, "Susan, turn off the light and go to sleep."
High school was the same thing, night time was my escape into reading. Unfortunately for my younger sister, we shared a room. The light kept her awake. Sometimes after she fell asleep, I turned on the light and read more. Again, my parents would yell up the stairs, "Susan, turn off the light and go to sleep."
My natural body rhythm wants to be awake and alert from around 11:00 p.m. until about 3:00 a.m. Then I like to sleep until the late morning hours. Don't ask me why. I can't explain it. Just like I can't explain why I'm left-handed. It's not better or worse than any other body rhythm schedule. It just is. Problem is, it doesn't conform to the majority of people's expectations of a normal sleep-wake cycle.
In my 20s and 30s I was a medical transcriptionist. I worked for major hospitals or private companies and was able to work swing shift which was perfect for me.
To this day, I enjoy staying up late. It's the best time for me to think and write. Just call me night owl.