Sixteen-year olds who typically sleep less than six hours per night are at 20 percent greater risk of becoming obese by age 21, compared to teens who sleep more than eight hours, according to a new study by researchers at the Mailman School of Public Health at Columbia University and the University of North Carolina Gillings School of Public Health.
The research, published in the Journal of Pediatrics, is the first to examine the long-term effect of sleeplessness on obesity in teenagers, providing the strongest evidence yet that lack of sleep raises risk for an elevated body mass index (BMI).
“Lack of sleep in your teenage years can stack the deck against you for obesity later in life,” says Shakira F. Suglia, Sc.D., assistant professor of epidemiology at the Mailman School.
“Once you’re an obese adult, it is much harder to lose weight and keep it off. And the longer you are obese, the greater your risk for health problems like heart disease, diabetes, and cancer.”
For the study, researchers analyzed health information from more than 10,000 American teens and young adults, ages 16 and 21, as part of the National Longitudinal Study of Adolescent Health. Height, weight, and sleep information was collected during home visits in 1995 and 2001.
Nearly one-fifth of the 16-year-olds reported getting less than six hours of sleep. These teens were 20 percent more likely to be obese by age 21, compared to their peers who got more than eight hours of sleep. While lack of physical activity and time spent watching television contributed to obesity, they did not account for the relationship between sleeplessness and obesity.
“The message for parents is to make sure their teenagers get more than eight hours a night,” said Suglia. “A good night’s sleep does more than help them stay alert in school. It helps them grow into healthy adults.”
The teens did not report their diets in the survey, although it could still play a role. Future research may investigate whether, for example, soda consumption is a factor in sleeplessness and, in turn, obesity.
Feeling sleepy and fatigued during the day is known to affect a person’s diet, by altering appetite and stimulating cravings. Energy levels may also play a role. For the sleep-deprived, eating calorie-dense fast food is easier than preparing a nutritious meal. According to the Centers for Disease Control and Prevention, teens should get nine to 10 hours of sleep per night.