I found this page convincing that polyphasic sleep won't be optimal for performance in practice, despite its obvious appeal

http://www.supermemo.com/articles/polyphasic.htm

""" Healthy body clock runs a 24 hour cycle. This cycle will make you sleepy during the subjective night (which can be midday too). This is why you won't be able to wake up from your nap in your subjective night without an alarm clock. Alarm clocks are unhealthy. They prevent sleep from fulfilling its function. The choice is yours: either (1) sleep polyphasically or (2) sleep naturally and let your brain develop its full intellectual potential. """