Participants in the study wore a tracker for two weeks each year, during the 14-year study. The trackers monitored their movements from 9 a.m. to 7 p.m. Since some downtime could be explained by watching television or reading a book, the technology used to determine the difference between the two was important.
“We have developed a unique algorithm to define naps and to differentiate naps from no activity. We didn’t define a specific length for ‘extended nap’ but we were more focused on the accumulated nap minutes per day and the change in the length of naps over the years.” Dr. Yue Leng, assistant professor of psychiatry at the University of California, San Francisco, told CNN.