Historian A. Roger Ekirch brought the trend of segmented sleep to light in 2001. His findings revealed that people used to divide their sleep into two separate periods, often referred to as "first sleep" and "second sleep." Between these periods, people would do chores, read, pray, or even go outside to visit friends.
Ekirch delved further into this phenomenon by studying modern non-Western cultures, including indigenous communities in Nigeria, Central America, and Brazil. He found that many of them also slept in segments. "During the period of nighttime wakefulness, Ekirch showed, different cultures elaborated rituals—of prayer, lovemaking, dream interpretation, or security checks—and while the rituals varied, the pattern itself was so pervasive as to suggest an evolutionary basis that somehow became disrupted in the modern West," Benjamin Reiss writes in New York Magazine.