Sleep regularity and patterns: circadian rhythms and biphasic sleep

Maintaining a regular sleep schedule can be more beneficial than simply aiming for a total of eight hours of sleep. According to Dr. Patricio Ochoa, consistency protects the circadian rhythm and prevents ‘social jet lag’—a phenomenon where significant shifts in sleep times during weekends cause a mismatch between internal biological clocks and social obligations.

While the body uses an internal 24-hour clock to regulate alertness and melatonin production, sudden changes in sleep and wake times force the body to constantly recalibrate, which can impact energy levels.

Additionally, research explores biphasic sleep, a pattern where sleep is divided into two periods. Historically, during the Middle Ages, people often slept for several hours, remained awake for a period of quiet activity, and then slept again until dawn. Modern studies, such as those observing the Hadza hunter-gatherer population in Tanzania, have also documented patterns of sleeping twice a day, though the specific structure may differ from historical European models.