Researchers from Brigham Young University studied the activity and sleep habits of 330 women over several weeks, looking for a relationship between their sleep behaviors and body composition. And they found it: The women whose bedtimes and wake times fluctuated by less than an hour every day had significantly lower body fat compared to those whose times varied more than 90 minutes. “We were surprised that consistency of sleep patterns were more important than sleep durations for predicting body fat,” says study author Bruce Bailey, PhD, a professor at BYU. But that doesn’t mean you can squeak by with a consistent few hours and call it good. How long you sleep still matters: The study also linked getting less than six and a half hours of sleep—or more than eight and a half nightly hours of shut-eye—with higher body fat percentages. So why does consistency matter so much? “It could be related to a change in physiology, but it could also be related to a more stressful, chaotic life,” says Dr. Bailey. In other words, not being able to set a consistent bedtime could be a symptom of a too-busy schedule that’s full of less than healthy choices. Another caveat: your sleep needs to be quality sleep—tossing and turning won’t do you any good. Study participants with better sleep quality were shown to have lower body fat. If quality sleep is more of a dream than a reality for you, check out these 20 ways to sleep better every night.
