For this small study, researchers wanted to look into how sleeping patterns influenced things like caloric intake, appetite, weight, fat distribution (i.e., body composition), and more. The participants were a group of 12 healthy, young to middle-aged adults, and the study took place over the course of two 21-day sessions with three months in between each session.
One group acted as the control, with a normal nine hours of sleep per night, while the other group only slept for four hours a night during a majority of the 21 days. After the first session and the three-month recovery period, the groups swapped, so the original control group then had to deal with a shorter night of sleep.
Throughout the study and afterward, metrics were taken to determine any behavioral or bodily changes that developed over the course of the study.
