I used to wake up and do things for a few hours and go back to bed...mostly in my 30's-40's....now, I sleep straight through 7-9 hours.

I also like to take naps...they don't interfere with my normal sleep...interesting article...

writer here: i have some pretty heavy plot action in my current WIP between first and second sleep. i'm using the darkness to the advantage of my character's intent.

I've been doing this for years. Asleep around 10. Wake at 2. Enjoy a couple hours of free time. Back asleep. Wake at 630

I heard about his book when it first cane out and have referred to it quite a bit.
That’s the ideal sleep pattern for me.

Interesting. I don't feel as rested if I fall asleep, wake up for a while, and then fall asleep again. But I also don't go to bed at dusk. When that happens, my "second sleep" is during morning daylight hours and the light makes it hard to stay asleep.