Wikipedia
Sleep pattern with more than one period of sleep in a 24-hour period
Summary
Polyphasic sleep or segmented sleep is the system of sleeping during multiple periods over the course of 24 hours, in contrast to monophasic sleep, a single period of sleep within 24 hours. Polyphasic usually means more than two periods of sleep, as distinct from biphasic sleep, meaning two periods of sleep. The term polyphasic sleep was first used in the early 20th century by psychologist J. S. Szymanski, who observed daily fluctuations in activity patterns.