BARCELONA, Spain — Many adolescents consider staying up late a rite of passage into adulthood. While burning the midnight oil can be fun occasionally, new research out of Spain warns that poor sleep habits among teens increases their risk of becoming overweight or obese.
More specifically, teens sleeping less than eight hours nightly are more likely to be overweight or obese in comparison to their more well-rested peers. Similarly, “shorter sleepers” are also more likely “to have a combination of other unhealthy characteristics” including excess fat around the waist, high blood pressure, and abnormal blood lipid or glucose levels.
“Our study shows that most teenagers do not get enough sleep and this is connected with excess weight and characteristics that promote weight gain, potentially setting them up for future problems,” says study author Mr. Jesús Martínez Gómez, a researcher in training at the Cardiovascular Health and Imaging Laboratory, Spanish National Center for Cardiovascular Research (CNIC), in a media release. “We are currently investigating whether poor sleep habits are related to excessive screen time, which could explain why older adolescents get even less sleep than younger ones.”
Night owl lifestyle putting teens’ health at risk
Study authors looked for any and all associations between sleep duration and measures of health among 1,229 adolescents enrolled in the SI! Program for Secondary Schools trial in Spain. The children had an average age of 12 and there was an equal number of boys and girls in the study. The team gauged sleep habits for seven days using a wearable activity tracker on three occasions — at ages 12, 14, and 16.
According to the American Academy of Sleep Medicine, six to 12-year-olds should sleep for nine to 12 hours nightly, while 13 to 18-year-olds should sleep for eight to 10 hours each night.
To simplify the research portion of this project, study authors classified eight hours or more of sleep per night as optimal across all age groups. After recording everyone’s sleep habits, researchers separated the teens into one of three groups: very short sleepers (less than 7 hours), short sleepers (7 to 8 hours), and optimal sleepers (8 hours or more).
BMI readings determined which children were overweight or obese. The research team carefully calculated “a continuous metabolic syndrome score” ranging from negative (healthier) to positive (unhealthier) values that encompassed waist circumference, blood pressure, and blood glucose and lipid levels.
At the age of 12, only 34 percent of participants were sleeping at least eight hours nightly. This statistic fell even further as the adolescents got older, falling to 23 percent at 14 years-old and 19 percent at 16 years-old. Boys tended to sleep even less than adolescent girls.
What about teens who get enough sleep?
Those children displayed better overall sleep quality, which means they woke up less frequently throughout the night and spent more time in bed actually sleeping in comparison to others with shorter sleep.
At 12 years-old, just over a quarter of these adolescents (27%) were either overweight or obese. At 14 years-old, that dropped to 24 percent, while 21 percent of well-rested teens were either overweight or obese at 16 years-old. Study authors were also sure to adjust for various factors such as parental education, migrant status, moderate-to-vigorous physical activity, smoking status, energy intake, city (Madrid or Barcelona), and their school before analyzing for associations between sleep duration, weight, and metabolic syndrome score.
At 12 years-old, “very short sleepers” were 21 percent more likely to be overweight or obese in comparison to optimal sleepers. By the age of 14, that increased risk profile jumped to an astounding 72 percent.
Meanwhile, adolescents in the “short sleepers” group were 19 percent and 29 percent more likely to be either overweight or obese in comparison with optimal sleepers at 12 and 14 years-old, respectively. Additionally, both very short and short sleepers displayed higher than average metabolic syndrome scores at ages 12 and 14.
“The connections between insufficient sleep and adverse health were independent of energy intake and physical activity levels, indicating that sleep itself is important. Excess weight and metabolic syndrome are ultimately associated with cardiovascular diseases, suggesting that health promotion programs in schools should teach good sleep habits. Parents can set a good example by having a consistent bedtime and limiting screen time in the evening. Public policies are also needed to tackle this global health problem,” Mr. Martínez Gómez concludes.
The study authors are presenting their findings at the ESC Congress 2022.