I recently read about how our sleeping patern of sleeping once per day may not have been the norm through history. Historical evidence suggests that people used to sleep in a polyphasic patern. They would go to sleep, wake up in the middle of the night for one hour, and then go back to sleep again.
source:
I read some information about polyphasic sleep recently and it was really interesting. In particular, some people have claimed to have experienced major benefits from changing their sleep pattern and napping every 4-6 hours. They say they feel more rested than normal and have gained considerably more waking time (but lucid dreaming is difficult). Here is a journal by somebody who undertook a polyphasic sleep schedule:
There is a topic in this forum about it:
[community.ld4all.com/t/polyphasic-sleep-its-over-d/37990/1)
seems like WBTB 
but a problem with the poliphasic sleep that involves sleeping every 4-6 hours is that it is incompatible with the social live of most people (i can’t just take a nap during school every day, forexample 
)
i read that most people who tried the “uberman” sleep cycle (taking 6 30minute long naps every 4 hours) had to stop at some point because it was not compatible with their lifestyle
i have to admit that I’m a bit sceptical about poliphasic sleep schedules that involve only a few hours of sleep, though