I think Ekirch's research is obviously correct but his conclusions might be a little off. it's well known already people tend to lose productivity during the afternoon in the modern day workplace. This is why the Europeans have their siesta
. Prior to the industrial era and the advent of lighting yes, we may have had our circadian clocks synced to this pattern prof. Ekirch talks about. However, it is Post-Industrial now, many countries around the world have constant non natural light and many individuals work around the clock and have varying shifts. As a result, the need for sleep - or "power naps" - hasn't changed, our clocks have just synced to a different schedule. Where you are in the world and the personal schedule you have will determine the optional time for that cat nap needed to recharge.
Again, it's not that we don't need to "sleep" twice in a day, more than likely we do. there is evidence
that points to its benefits, however as we are finding out with medicine today, it would be and should be tailored to the individual and their schedule.