Another random fun thing I realized. I addition to being a lot like the first half of the reported archaic human bimodal sleep, an Everyman core sleep is also a lot like the first phase of the night's sleep done in the Wake-Back-To-Bed lucid dream induction technique.

Just tried a WBTB with 5 hours of initial sleep, and it led to a lucid dream (slept another 3 hours afterwards). 5 hours is pretty close to the Everyman-2 core sleep. I wonder if, in addition to being potentially nice for lucid dreams, adopting a bimodal schedule for a full night's sleep could be used as a stepping stone to adopting an Everyman sleep schedule, since you're training yourself to sleep no more than 4+ hours at a time.