Unbeknown to Ms. Rafea, she had naturally reverted back to a sleep cycle that was believed to be standard in multiple culturesin the late Middle Ages through the early 19th century.

During that time, many people went to sleep around sundown and woke three to four hours later. They socialized, read books, had small meals and tried to conceive children for the next hour or two before going back for a second sleep for another three to four hours. It was only when artificial light was introduced that people began forcing themselves to sleep through the night, said A. Roger Ekirch, a professor of history at Virginia Tech and the author of “The Great Sleep Transformation.”

Now that many people are making their own schedules, working from home and focusing more on self-care, there has been a return for some to the idea of a segmented sleep cycle — voluntary and, given the stress levels of the last two years, not.