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.Cool! I do that sometimes, going to bed early, then waking for an hour or so, then falling back to sleep to await the morning alarm. Milady and I do this frequently enough that we call it "vampire-ing". As in "I vampired for a couple of hours last night.
As I understand the article, sleeping eight full hours is a fairly recent invention, since the time that electric lights were invented. It seems that our forefathers thought that sleeping twice per night was perfectly common.