Over the course of three years, the researchers had the participants check in weekly and report their sleeping habits from the previous week. The researchers tracked the health of the participants for five years following the end of the three-year period.
Nearly 60 percent of participants said they were not napping. Around one in five said they napped one or two times per week. Almost a quarter said they took three or more naps per week. (The researchers observed 155 fatal and non-fatal cardiovascular disease events during the monitoring period.)
This is actually a subject of fierce debate. Sleep researchers have never officially defined the nap, and different cultures view naps differently. (How long is a nap? I would say between 10 minutes and three hours, but that’s just me.) Sleep researchers say a nap between 20 and 30 minutes in the early afternoon is the perfect nap.