Is sleep really necessary in eight-hour blocks?

A recent article in BBC magazine looked into the history of the debate over the best way to sleep.

Turns out there are historical accounts that suggest people centuries ago did not sleep for eight straight hours. They are reports that people would sleep for four hours, wake up for a few hours in the middle of the night, then get another four hours later.

One document even noted prayers written especially for that awake time at night.

The article also explains that the advent of street lights in the 1600s might have had to do with the slow dissolution of that four and four model -- known as a bi-modal -- and more towards an eight-hour block.

So are we doing it wrong? Were our bodies really designed to just sleep in a four-hour blocks?

Michel Cramer Borneman of the Minnesota Regional Sleep Disorders Center at HCMC in Minneapolis spoke to The Daily Circuit about the report. We have to be careful not to take too simplistic a view of human sleep, he said.