Teenagers who sleep less than seven hours a night are up to 70 per cent more likely to be obese or overweight, a study claims.
Getting between seven to eight hours also raised the risk of piling on the pounds by up to 29 per cent compare to those who got a full eight hours.
Spanish researchers who did the study said it showed why teens should aim for eight hours sleep at an absolute minimum.
Losing out on sleep can cause the body to produce the hunger hormone ghrelin, which makes people eat more — putting them at greater risk of obesity.
The study of more than 1,200 children aged 12 to 16 measured their sleeping over a week and compared it to their body-mass index (BMI).
It found 14-year-olds who slept less than seven hours a night were 72 per cent more likely to have a BMI of over 25 than those sleeping more than eight.
Researchers said parents should ‘set a good example’ by enforcing strict bedtimes to avoid their children being at risk of heart problems because of weight gain.
It comes amid a growing childhood obesity epidemic that means one in five youngsters in England are too fat by the time they start primary school.
Researchers from the Spanish National Centre for Cardiovascular Research in Madrid found teens that miss out on the recommended minimum sleeping time were more likely to be fat
Childhood obesity reached ‘unprecedented levels’ during the Covid pandemic, with children sat at home and not able to run around in playgrounds.
The NHS recommends teenagers get between seven and 11 hours of sleep a night to develop physically and mentally.
Previous studies have also shown missing out on sleep can lead to a host of health problems in later life including high blood pressure, dementia and diabetes.
The latest research was presented as an abstract at the European Society of Cardiology Congress 2022 today.
Researchers used data from a trial of 1,229 secondary school children in 2019 in Spain to see how sleep affected their weight.
Children were split into groups of 12-year-olds, 14-year-olds and 16-year-olds.
Their BMIs were recorded to see whether they were underweight, a normal weight, overweight or obese. This factored in their age, height and gender.
Overall, 27 per cent of 12-year-olds, 24 per cent of 14-year-olds were and 21 per cent of 16-year-olds were overweight or obesity.
Researchers also measured their waist circumference, blood pressure, cholesterol and blood sugar levels to check how healthy they were more broadly.
The teens were given sleep trackers to wear on their wrists over a week to measure how much shut-eye they got.
Only 34 per cent of 12-year-olds slept at least eight hours, while the figure was lower for those aged 14 (23.4 per cent) and 16 (19.4 per cent).
Boys and children from ethnic minority families tended to sleep for shorter periods, researchers said.
After adjusting for exercise and diet, researchers found 12-year-olds who slept less than seven hours a night were a third more likely to be overweight or obese than those who got at least eight hours.
Twelve-year-olds who slept between between seven and eight hours were a fifth more likely to fall into the category.
Both groups were also more likely to have larger waist lines and higher blood pressure, cholesterol and blood sugar levels.
The researchers did not detail why the lack of sleep was fuelling obesity.
But previous studies have shown losing sleep can drain energy over the day, making people less likely to exercise and more prone to snacking.
Jesus Martinez Gomez, a cardiologist at the Spanish National Centre for Cardiovascular Research in Madrid, suggested schools should ‘teach good sleep habits’.
He said: ‘The connections between insufficient sleep and adverse health were independent of energy intake and physical activity levels, indicating that sleep itself is important.
‘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.’
Chloe MacArthur, senior cardiac nurse at the British Heart Foundation, said: ‘Getting enough sleep is crucial during adolescence as it supports healthy development as well as good physical and mental health.
‘However, it’s not just teenagers who should prioritise a good night’s sleep, as getting enough shut-eye is vital for both our general wellbeing and for maintaining good heart health throughout life.
‘Sleep isn’t the only factor to consider and it’s important to look at your lifestyle as a whole.
‘Knowing your numbers such as blood pressure and cholesterol levels, maintaining a healthy weight and getting regular physical activity, cutting down on salt and alcohol intake, and eating a balanced diet are essential help to keep your heart healthy at every age.’