Biphasic sleep patterns and historical context

Biphasic sleep, a pattern where rest is divided into two distinct periods within a 24-hour cycle, is a subject of ongoing scientific and historical study. Historically, as documented by historian Roger Ekirch, many people in Europe during the Middle Ages and Early Modern periods practiced a form of segmented sleep. This often involved a ‘first sleep,’ a period of wakefulness for reading, praying, or socializing, followed by a ‘second sleep.”

The shift toward continuous, monophasic sleep is largely attributed to the Industrial Revolution, the introduction of artificial lighting, and the standardization of factory work schedules. While modern norms emphasize a single eight-hour block, researchers note that sleep needs vary by individual.

Scientific consensus suggests that the quality of rest depends on total sleep duration and alignment with circadian rhythms rather than the number of segments. While biphasic sleep may offer alternatives for shift workers or those with irregular schedules, experts state there is insufficient evidence to claim it is superior to continuous sleep.