A study found that teens who sleep less than seven hours a night are 70% more likely to be obese or overweight.
And the duration of seven to eight hours also increased the risk of weight gain by 29% compared to those who exercised all eight hours.
The Spanish researchers who conducted the study said it showed why teenagers need at least eight hours of sleep.
Lack of sleep can cause the body to produce the hunger hormone ghrelin, so they eat more, increasing their risk of obesity.
A study of more than 1,200 children aged 12 to 16 measured their sleep over the course of a week and compared it to their body mass index (BMI).
The study found that 14-year-olds who slept less than seven hours a night were 72% more likely to have a BMI over 25 than those who slept more than eight hours.
The researchers said parents should “set a good example” by setting strict bedtimes so as not to put their children at risk of heart disease due to being overweight.
This is happening against the backdrop of an epidemic of childhood obesity, which means that one in five children in England are obese by the time they enter primary school.
Childhood obesity has reached “unprecedented levels” during the Covid pandemic, with children staying at home and unable to run on playgrounds.
The National Health Service (NHS) recommends that teenagers get between seven and 11 hours of sleep every night for their physical and mental development.
Previous research has also shown that sleep deprivation can lead to a number of health problems later in life, including high blood pressure, dementia and diabetes.
The latest study was presented as an extract in CONSPIRACY European Society of Cardiology 2022.
The researchers used data from a 2019 study of 1,229 high school students in Spain to see how sleep affects their weight.
The children were divided into groups of 12, 14 and 16 years old.
Their BMI was recorded to see if they were underweight, normal weight, overweight, or obese. This is taken into account by age, height and gender.
Overall, 27% of 12-year-olds, 24% of 14-year-olds, and 21% of 16-year-olds were overweight or obese.
The researchers also measured their waist circumference, blood pressure, cholesterol and blood sugar levels to check their health more widely.
Teens were given sleep trackers to wear on their wrists for a week to measure how well they sleep.
Only 34% of 12-year-olds slept at least eight hours, while this rate was lower for 14-year-olds (23.4%) and 16-year-olds (19.4%).
Researchers say boys and children from ethnic minority families tend to sleep less.
After adjusting for exercise and diet, the researchers found that 12-year-olds who got less than seven hours of sleep per night were one third more likely to be overweight or obese than those who got at least eight hours of sleep.
Twelve-year-olds who slept between seven and eight hours were one-fifth more likely to fall into this category.
Both groups were more likely to have a larger waist and higher blood pressure, cholesterol and blood sugar levels. Researchers do not elaborate on how lack of sleep increases obesity.
But previous research has shown that lack of sleep can sap energy throughout the day, making people less likely to exercise and more prone to snacking.
Parents can set a good example by setting regular bedtimes and reducing screen time in the evening.
Chloe MacArthur, cardiologist at the British Heart Foundation, said: “Adequate sleep is critical during adolescence as it promotes healthy growth as well as good physical and mental health.
However, teens shouldn’t just prioritize a good night’s sleep because getting enough sleep is vital to our overall well-being and lifelong heart health.
Source: Daily Mail