Teenagers who sleep less than eight hours a night are more likely to be overweight or obese compared to their peers who get enough sleep, according to research presented at ESC Congress 2022. Those who sleep less were also more likely to have a combination of other unhealthy characteristics, including excess abdominal fat, elevated mean blood pressure, and abnormal blood lipid and glucose levels.
“Our study shows that most adolescents do not get enough sleep and this is related to excess weight and characteristics that promote weight gain, which could lead to future problems,” said study author Mr. Jesús Martínez Gómez, researcher in training at the Cardiovascular Imaging and Health Laboratory, National Center for Cardiovascular Research (CNIC), Madrid, Spain. "We are currently investigating whether poor sleep habits are related to excessive screen time, which could explain why older adolescents sleep even less than younger ones."
This study examined the association between sleep duration and health in 1229 adolescents in the Secondary School Trial Program in Spain. Participants had an average age of 12 years at the beginning of the study with an equal number of boys and girls.
Sleep was measured over 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 recommends 9 to 12 hours of sleep per night for children ages 6 to 12 and 8 to 10 hours for children ages 13 to 18. To simplify the analysis, the study used 8 hours or more as optimal. Participants were classified as very short sleepers (less than 7 hours), short sleepers (7 to 8 hours), and optimal sleepers (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 (poorer) values that included waist circumference, blood pressure, and blood glucose and lipid levels.
At age 12, only 34% of participants were sleeping at least 8 hours per night, and this dropped to 23% and 19% at ages 14 and 16, respectively. Children tended to sleep less. Teens who slept more also had better quality sleep, meaning they woke up less during the night and spent a greater proportion of their time sleeping in bed compared to those who slept less. The prevalence of overweight/obesity was 27%, 24% and 21% at ages 12, 14 and 16, 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 consumption, city (Madrid or Barcelona) and school.
Compared with optimal sleepers, overweight/obesity was 21% and 72% more likely in very short sleepers at ages 12 and 14, respectively. Poor sleepers were 19% and 29% more likely to be overweight/obese compared to optimal sleepers at ages 12 and 14, respectively. Similarly, both very poor and short sleepers had higher mean metabolic syndrome scores at ages 12 and 14 compared to optimal sleepers.
Mr Martínez Gómez said: “The connections between lack of 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 disease, 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 address this global health problem.”
