The New York Times dissects some surprising findings in a recent sleep study that used actigraphy to measure sleep.
It has always been difficult to ascertain how much people sleep; survey questions are unreliable (how can you tell when you’ve dozed off?), and wiring people with electrodes creates such an abnormal situation that the results may bear little resemblance to ordinary nightlife.
Enter the actigraph, a wrist-motion monitor. “The machines have gotten better, smaller, less clunky and more reliable,” said Linda Waite, a sociologist and a co-author of the study.