Most teenagers will be getting less sleep now that school has started again for the fall which means their chances of gaining weight could go up. That’s according to new research from the European Society of Cardiology which found teenagers who don’t get enough sleep are more likely to be overweight or obese compared to their well-rested peers.
Sleep deprived teens are also more likely to have a combination of other health issues such as excess abdominal fat, elevated blood pressure, elevated blood sugar and abnormal blood lipid 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."
The study looked at the sleep habits of more than 1,200 adolescents evenly divided between boys and girls beginning at the age of 12 as part of the Program for Secondary Schools trial in Spain. Their sleep was tracked with wearable activity trackers for a total of seven days on three separate occasions when the kids were 12, 14 and 16.
The American Academy of Sleep Medicine recommends a minimum of 9 hours for children up to the age of 12 and a minimum of eight hours between the ages of 13-18. Researchers used the figure of 8 hours for the sake of simplicity during the trial period.
Participants were divided into the categories of very short sleepers, those who got an average of less than 7 hours per night, short sleepers, those with 7-8 hours, and optimal sleepers, those who got 8 hours or more per night.
The participants were measured for weight according to body mass index. They were also scored for a list of metabolic factors using a ranking system for waist circumference, blood pressure, blood glucose and lipid levels.
Unfortunately, lack of adequate sleep was prevalent through all age groups. Only 34% of 12-year-olds got at least 8 hours of sleep per night. That number dropped to 23% by the age of 14 and just 19% of the 16-year-olds slept at least 8 hours. Boys tended to get less sleep across the board compared to girls.
The teens who got the most sleep also reported better quality sleep. That means they woke up less and spent a greater percentage of their time in bed than those who slept less.
The association between sleep and weight and metabolic issues was calculated by age group and then adjusted for things such as parental education, migrant status, activity levels, smoking status, geographic location and others.
The percentage of overweight/obese by age group was 27% for 12-year-olds, 24% for 14-year-olds and 21% for 16-year-olds. Compared to optimal sleepers, the prevalence of overweight/obesity was 21% higher for 12-year-olds in the very short sleep group and 19% higher in short sleepers group. It was higher among 14-year-olds who were 72% more likely to be overweight/obese in the very short sleep category and 29% more in the short sleep group.
The metabolic scores of the participants were also worse at the ages of 12 and 14 for those who slept less than the optimal amount.
"The connections between insufficient sleep and adverse health were independent of energy intake and physical activity levels, indicating that sleep itself is important," Martínez Gómez said. "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."