Linked: Sleeping Twice
His research found that we didn’t always sleep in one eight hour chunk. We used to sleep in two shorter periods, over a longer range of night. This range was about 12 hours long, and began with a sleep of three to four hours, wakefulness of two to three hours, then sleep again until morning. - SlumberWise
If waking up, getting an idea, writing it down and going back to sleep counts, than I still do this kind of thing. Interesting article.