The study also found that short-sleepers were more likely to have unhealthy characteristics such as elevated blood pressure or abnormal glucose levels.
Teenagers who sleep less than 8 hours are more likely to be overweight and obese.
According to a study presented at the European Society of Cardiology (ESC) Congress 2022, adolescents who sleep fewer than eight hours per night are more likely to be overweight or obese than their peers who get enough sleep. Shorter sleepers were also more likely to have a mix of other unhealthy characteristics such as excess abdominal fat, high blood pressure, and abnormal blood lipid and 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,” said study author Mr. Jesús Martínez Gómez, a researcher in training at the Cardiovascular Health and Imaging Laboratory, Spanish National Centre 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 get even less sleep than younger ones.”
This research looked at the relationship between sleep duration and health in 1,229 Spanish teenagers participating in the SI! Program for Secondary Schools trial. At baseline, participants had an average age of 12 years, with an equal number of males and girls.
At ages 12, 14, and 16, each participant had their sleep throughout the course of a seven-day period measured by a wearable activity tracker three times. The American Academy of Sleep Medicine recommends 9 to 12 hours of sleep each night for children aged 6 to 12, and 8 to 10 hours for those aged 13 to 18. To simplify the analysis, the researchers determined that 8 hours or more were ideal. Participants were divided into three groups: extremely short sleepers (less than 7 hours), short sleepers (7 to 8 hours), and optimal sleepers (8 hours or more).
Body mass index was used to determine overweight and obesity. The researchers created a continuous metabolic syndrome score that ranged from negative (healthier) to positive (unhealthier) values based on waist circumference, blood pressure, blood glucose, and lipid levels.
Only 34% of individuals aged 12 slept for at least 8 hours every night, and this declined to 23% and 19% at 14 and 16 years old, respectively. Boys slept less than girls. Teenagers who slept the most had better quality sleep, meaning they woke up less throughout the night and spent a greater percentage of their time in bed asleep than those who slept the less. At 12, 14, and 16 years of age, the prevalence of overweight/obesity was 27%, 24%, and 21%, 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.
Mr. Martínez Gómez said: “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.”
Meeting: ESC Congress 2022
The SI! Program for Secondary School trial is funded by the Carlos III Institute of Health (ISCIII)-Fondo de Investigacion Sanitaria, the Fundació la Marató de TV3, ‘la Caixa’ Foundation, the Ministerio de Ciencia e Innovación, the Generalitat de Catalunya, and the SHE Foundation. Jesús Martínez-Gómez, the first author of the study, is a postgraduate fellow of the Ministerio de Ciencia e Innovación of Spain at the Residencia de Estudiantes (2020–ongoing). Rodrigo Fernández-Jiménez, group leader of the Cardiovascular Health and Imaging lab, is recipient of grants from the ISCIII-Fondo de Investigación Sanitaria and the European Regional Development Fund/European Social Fund. The CNIC is supported by the ISCIII, the Ministerio de Ciencia e Innovación (MCIN) and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence.
The authors do not have any conflicts of interest in relation to this study.