Is it possible that we've completely rewritten our understanding of how people have always lived? Sure it is!

In 2001, historian Roger Ekirch of Virginia Tech published a seminal paper, drawn from 16 years of research, revealing a wealth of historical evidence that humans used to sleep in two distinct chunks.

His book At Day's Close: Night in Times Past, published four years later, unearths more than 500 references to a segmented sleeping pattern—in diaries, court records, medical books and literature, from Homer's Odyssey to an anthropological account of modern tribes in Nigeria.