I read about that a while back. Makes sense before artificial light.

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...

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.

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.

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.