You may want to start DVRing Jimmy Kimmel Live — because the time you go to bed can have an impact on the size of your belly.
Researchers from University of California, Berkeley, examined bedtime and BMI (body mass index) data taken from 3,342 adolescents over a 15-year period (between 1994 and 2009).
The results, which were published in the October issue of the journal Sleep, indicate that later-than-average weeknight hit-the-hay time equated to higher numbers on the scale. Over the course of five years, the study participants gained, on average, 2.1 points on the BMI index for each lost hour of sleep. (The BMI range for a healthy adult is 18.5 to 24.9 — a variation of just 6.4 points.)
Interestingly enough, this effect was based solely on bedtime and had nothing to do with total hours of sleep — participants who got eight hours of sleep per night still saw weight gain if they went to bed late. Exercise frequency and screen time were also not factors in this equation; however, fast food consumption was found to be a “significant partial mediator” between snooze time and the scale.
“These results highlight adolescent bedtimes, not just total sleep time, as a potential target for weight management during the transition to adulthood,” stated Lauren Asarnow, lead author of the study and a doctoral student at UC Berkeley’s Golden Bear Sleep and Mood Research Clinic, in a press release.
This isn’t the first time we’ve heard that slumber and size go hand in hand. In June 2013, a study from the American Academy of Sleep Medicine found that healthy adults who went to bed in the wee hours of the night and dealt with chronic sleep restriction were at an increased risk for gaining weight, due to their love of late-night snacks. Also, in early 2015, research presented at the annual meeting of the Endocrine Society in San Diego stated that losing just 30 minutes of shut-eye on weeknights can have long-term negative health consequences, including a higher risk of obesity (up to 72 percent) and insulin resistance (up to 39 percent), which can promote the onset of type 2 diabetes.
“Sleep and appetite are deeply connected,” Michael J. Breus, PhD, a clinical psychologist with a specialty in sleep disorders and author of The Sleep Doctor’s Diet Plan: Lose Weight Through Better Sleep, tells Yahoo Health. “Poor sleep makes us more tempted by junk food and more inclined to consume greater amounts of food.”
He refers to a previous study conducted at Brandeis University that found a molecule in the brains of fruit flies that was linked to regulating appetite, as well as modulating sleep and activity levels. “With hundreds of millions of adults and children in the U.S. and around the world struggling with obesity and its related health risks, discoveries like these — and the treatments that may eventually stem from them — can’t come often enough.”