If you're a nightowl, you might want to rethink your sleeping schedule.
A new study by University of California Berkeley published in the journal Sleep this month links a person's body mass index and sleep.
The UC Berkeley researchers found that adolescents and teenagers who go to sleep way past their bed time is more likely to gain weight as compared to their peers to sleep early. To gather data, the researchers analyzed 1994 to 2009 data on more than 3,300 teens available at the National Longitudinal Study of Adolescent Health which has observed and recorded US Teenagers' influences and behaviours.
"Obesity is obviously growing among adolescents and adults, and there's also an epidemic of lack of sleep and later bed time preference in teens," informs study author Lauren Asarnow, a doctoral candidate at the University of California, Berkeley in a statement to CBS News. "There's been some literature looking at the relationship late bedtimes and weight gain cross-sectionally, but no one's ever looked at what happens long term," she adds.
According to the National Institutes of Health, as per CBS News, a normal Body Mass Index (BMI) range for adults must fall between 18.5 and 24.9. On the other hand, an individual is considered overweight if his computed BMI is 25 to 29.9. A BMI of 30 or greater is defined as obesity.
"These results highlight adolescent bedtimes, not just total sleep time, as a potential target for weight management during the transition to adulthood," says Arsenow.
CBS reports that the study's findings revealed for every hour of sleep lost, a 2.1 point increase in BMI is computed. The "gain" is said to have approximately occurred over a five-year period.
"Conceivably, if you're going to bed an hour later, over time you could be shifting BMI categories from normal to overweight," Asarnow clarifies as per CBS. "So even a two-point increase could be clinically significant."
Using the survery, the UC Berkeley researchers deduced that many teenagers do not sleep get the recommended nine hours of sleep. In addition, these teens are reported to have had difficulty staying awake in school. "The human circadian rhythm, which regulates physiological and metabolic functions, typically shifts to a later sleep cycle at the onset of puberty," the UC Berkeley report notes.
According to lead author Asarnow, the findings in the same way suggest that adolescents who go to bed earlier will "set their weight on a healthier course as they emerge into adulthood."
On a more positive note, Asarnow expresses that their study had more pressing implications. "The good news is sleep is a highly modifiable," she remarks. "If you could shift bedtime in the teenage years, you can create good sleep habits and maybe prevent weight gain over time."