If you're looking for a fairly painless way to lose weight, researchers at Brigham Young University have a new solution for you: Put yourself on a regular sleep schedule. People who keep a regular sleep routine have a lower body fat than those who keep irregular sleep hours, says a new study. Led by Bruce Bailey, professor of exercise science, researchers followed 300 female college students aged 19 to 26, who were given activity trackers to watch their movements and activities, including waking and sleeping times . Researchers also measured their body composition  before and after the one-week study period. What the researchers found: Body fat varied with sleep quantity. Women who slept between 8 and 8.5 hours a night had the lowest body fat. While those who slept less than 7 hours or over 9 hours had higher body fat. High quality sleep was associated with lower body fat while poor sleep was connected with higher body fat. Waking and going to sleep at the same time every day was most strongly linked with lower body fat. The difference in body weight was greater with more variation in sleep pattern. Women whose sleep patterns varied by 90 minutes a night had higher body fat than those whose sleep patterns varied by 60 minutes or less on average. The study followed up on a body of research conducted over the last few years that ties quality and quantity of sleep to weight loss and better weight control. While researchers don't know exactly how sleep schedules affect body weight and fat, other studies have shown that sleep has an effect on physical activity, appetite , and the hormones that control metabolism , and the signals that tell us we're full. Which of the following about the study led by Bruce Bailey is true?
The participants included both females and males. The participants' activities were monitored through trackers. The participants' body composition were measured only after the study. The study was controlled by researchers during a long period time.