I don’t particularly like the general approach taken by the author to suggest that biphasic sleep is less ideal or somehow less natural. I believe, in the same way that the author suffers from insomnia and most other humans do not (statistically speaking) that it simply represents the genetic diversity among humans. This is both Occam’s razor as well as what is supported in sleep literature and by the simple existence of disorders which directly effect sleep phases.

With that being said, it is an interesting look into some of the history of biphasic and polyphasic sleep schedules, but somehow the author seemed to fail to note it’s existence throughout a much more extended history - there are references to differing sleep patterns in Titus Livius’s Ab Urbe Condita Libri (although I would not blame anyone for not reading all 142 books in this collection), for example, and other anthropological thoughts on alternative sleeping patterns which go back quite far in history. It should be unsurprising that as diverse as humans are that our patterns and quality of sleep would naturally reflect that.