Insufficient sleep in teenagers, defined as less than eight hours a night, is linked with obesity, according to new research.

Shorter sleepers were also more likely to have a combination of other unhealthy characteristics including excess fat around the middle, elevated blood pressure, and abnormal blood lipid and glucose levels. The research on insufficient sleep in teenagers was presented at the European Society of Cardiology Congress 2022.

“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 Jesús Martínez Gómez, a researcher in training at the Cardiovascular Health and Imaging Laboratory, Spanish National Centre for Cardiovascular Research (CNIC), Madrid, Spain, in a statement. “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.”

This study examined Insufficient sleep in teenagers by looking at the association between sleep duration and health in 1,229 adolescents in the SI! Program for Secondary Schools trial in Spain. Participants had an average age of 12 years at baseline with equal numbers of boys and girls.

Sleep was measured for seven days with a wearable activity tracker three times in each participant at ages 12, 14 and 16 years. For optimal health, the American Academy of Sleep Medicine advises sleeping 9 to 12 hours a night for 6 to 12-year-olds and 8 to 10 hours for 13 to 18-year-olds. To simplify the analysis, the study used 8 hours or more as optimal. Participants were categorized as very short sleepers (less than 7 hours), short sleepers (7 to 8 hours), and optimal (8 hours or more).

Overweight and obesity were determined according to body mass index. The researchers calculated a continuous metabolic syndrome score ranging from negative (healthier) to positive (unhealthier) values that included waist circumference, blood pressure, and blood glucose and lipid levels.

At 12 years of age, only 34% of participants slept at least 8 hours a night, and this dropped to 23% and 19% at 14 and 16 years of age, respectively. Boys tended to get less sleep. Teenagers who got the most sleep also had better quality sleep, meaning they woke up less during the night and spent a higher proportion of the time in bed sleeping compared to those with shorter sleep. The prevalence of overweight/obesity was 27%, 24% and 21% at 12, 14 and 16 years of age, respectively.

Associations between sleep duration, overweight/obesity and metabolic syndrome score were analyzed after adjusting for parental education, migrant status, moderate-to-vigorous physical activity, smoking status, energy intake, city (Madrid or Barcelona) and school.

Compared with optimal sleepers, overweight/obesity was 21% and 72% more likely in very short sleepers at 12 and 14 years, respectively. Short sleepers were 19% and 29% more likely to be overweight/obese compared with optimal sleepers at 12 and 14 years, respectively. Similarly, both very short and short sleepers had higher average metabolic syndrome scores at 12 and 14 years compared with optimal sleepers.

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