Researchers examine effect of sleeplessness on obesity in teenagers over time

Teenagers who don't get enough sleep may wake up to worse consequences than nodding off during chemistry class. According to new research, risk of being obese by age 21 was 20 percent higher among 16-year-olds who got less than six hours of sleep a night, compared with their peers who slumbered more than eight hours. (The Centers for Disease Control and Prevention recommends nine to ten hours of sleep for teenagers.)

Researchers at the Mailman School of Public Health at Columbia University and the University of North Carolina Gillings School of Public Health are the first to examine the effect of sleeplessness on obesity in teenagers over time, providing the strongest evidence yet that lack of sleep raises risk for an elevated BMI. Results appear in Journal of Pediatrics.

Shakira F. Suglia, ScD, assistant professor of Epidemiology at the Mailman School, and colleagues 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. Information on height and weight and sleep 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. This group was 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.

"Lack of sleep in your teenage years can stack the deck against you for obesity later in life," says Suglia. "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."

"The message for parents is to make sure their teenagers get more than eight hours a night," adds Suglia. "A good night's sleep does more than help them stay alert in school. It helps them grow into healthy adults."

Daytime sleepiness and fatigue are known to affect what and how people eat, by altering appetite and stimulating cravings. Energy levels may also play a role. For the sleep-deprived, ordering calorie-dense fast food is easier than preparing a nutritious meal. Information on what the teens ate was not captured in the surveys, although it could play a role. Future research may look whether, for example, soda consumption is a factor in sleeplessness and, in turn, obesity. (A 2013 study by Suglia found young children who drink soda are more likely to have behavioral problems.)