Dear teens, if you're worried about putting extra pounds, you better sleep early.
A new study conducted by UC Berkeley researchers not only established that sleeping late is correlated to weight gain, but it also specifically measured how much you can gain based on the possible increase to the body mass index (BMI). BMI is one of the most common measurement tools of weight gain and obesity and is determined by comparing the person's actual weight to height.
In this study, the team worked on the available data found in a national longitudinal study that focused on adolescent health. It followed hundreds of teens starting in 1994 and assessed their behaviors including sleeping habits and weight changes.
As comparison, the researchers determined three periods for analysis: the time they began experiencing adolescence, the years they were in college, and the moment they reached young adulthood. The range of years was from 1994 to 2009. In these three periods, they gathered the information pertaining to bedtimes and BMI. The bedtimes were self-reported while the BMI was identified by the researchers.
Based on the results of the Berkeley study, in general, those who slept late at night gained weight than those who slept early. To be more specific, the BMI increased by at least 2.1 points for every hour of loss of sleep, which could occur for a period of around five years.
If that isn't some bad news, exercising didn't really help in controlling the weight gain, nor would possibly extending sleeping hours to compensate.
The survey results also agreed with other independent studies that revealed how teens tend to be more sleep deprived, including finding it difficult to wake up early for school. But this is more than just a deliberate habit. A person's body clock changes in different periods, and for teens, their sleep cycle is late.
Nevertheless, the researchers believe that their study can be helpful in managing teen weight by looking more into the time they sleep rather than the total number of hours of sleep.
The study is led by Lauren Asarnow, a doctoral student of Golden Bear Sleep and Mood Research Clinic and Teen Sleep study researcher. She is also a University of Carolina psychiatry intern. Working with her on this were Columbia University's Eleanor McGlinchey and UC Berkeley's Allison Harvey, who both served as her co-authors.
The study is available in Sleep.