Hugh Pickens writes "BBC reports that a growing body of evidence from both science and history suggests that eight-hours of uninterrupted sleep may be unnatural as a wealth of historical evidence reveals that humans used to sleep in two distinct chunks called first and second sleep. A book by historian Roger Ekirch, At Day's Close: Night in Times Past, 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. 'It's not just the number of references — it is the way they refer to it, as if it was common knowledge,' says Ekirch. References to the first and second sleep started to disappear during the late 17th Century with improvements in street lighting, domestic lighting and a surge in coffee houses — which were sometimes open all night. Today most people seem to have adapted quite well to the eight-hour sleep, but Ekirch believes many sleeping problems may have roots in the human body's natural preference for segmented sleep which could be the root of a condition called sleep maintenance insomnia, where people wake during the night and have trouble getting back to sleep. 'Our pattern of consolidated sleep has been a relatively recent development, another product of the industrial age, while segmented sleep was long the natural form of our slumber, having a provenance as old as humankind,' says Ekrich, adding that we may 'choose to emulate our ancestors, for whom the dead of night, rather than being a source of dread, often afforded a welcome refuge from the regimen of daily life.'"