Polyphasic sleep is a method of training your body to requiring much less sleep by taking multiple short naps throughout the day instead of one long sleeping time at night. Over at Quartz, science-trained journalist Akshat Rathi reports on his year-long experiment attempting to "cheat sleep."
Sleep expert Claudio Stampi explained in his 1992 book Why We Nap: Evolution, Chronobiology, and Functions of Polyphasic and Ultrashort Sleep that humans shouldn't find it hard to adjust to a polyphasic schedule.
Many animals are known to be polyphasic sleepers, and our hunter-gatherer ancestors may have been too. But we don't even need to go so far back in time to find examples of polyphasic humans.
As Roger Ekirch notes in At Day's Close: A History of Nighttime, a segmented sleep pattern was common as recently as the 18th century.
Back then people often slept for four hours, then woke up for an hour or two before going back to bed for another four hours. In the period they were awake at night, people smoked, had sex, and even visited neighbors. It was the advent of night-time lighting that allowed us to squeeze in more awake time doing things and made people adapt to what is today's monophasic sleep.