Teenagers who don't get enough sleep are more likely to develop heart disease later in life, Canadian research has found.
Researchers studied 4,000 young people and found the one-third with the poorest sleep quality were more likely to be overweight or have unhealthy blood pressure or cholesterol levels.
Poor sleep was defined as problems falling or staying asleep, night time 'restlessness' and bad dreams, among other things.
A good excuse for a lie-in: The more sleep teenagers get, the lower their risk of heart disease later in life While the findings do not prove that sleep problems are to blame for heart disease, it's known that poor sleepers tend to take less exercise, spend more time in front of the TV and eat a worse diet than their better-rested counterparts.
That was also true of the sleep-deprived teens in this study.
But even when the researchers factored those things in, poor sleep was still linked to a higher rate of potential heart risks.
'When people think about cardiovascular risk, sleep doesn't usually come up,' said senior researcher Dr. Brian C. McCrindle, of the Hospital for Sick Children in Toronto, Canada.
'These findings give more evidence that sleep is one of the things people should think about.'
The study, published in the Canadian Medical Association Journal, asked 4,100 teenagers about their sleep quality.
All of the teenagers were healthy, but the third with the worst sleep scores showed signs of potential heart trouble in the future.
Overall, 48 per cent were either overweight, had elevated blood pressure or high cholesterol.
Only 39 per cent of the well-rested teenagers had these symptoms.
The findings are worrying because these risk factors for heart disease, such as being overweight or having high cholesterol, tend to continue into adulthood, said Dr McCrindle.
Previous research in adults has linked poor sleep to heart disease and diabetes.
One theory is that getting too little sleep could have negative effects on certain hormones, including those that regulate appetite and fat metabolism.
People who are awake late at night may also have more chances to snack, and less energy to exercise the next day.
Studies suggest that half of teenagers get fewer than seven hours of sleep on week nights.
Yet up to nine hours is much better, say the researchers, adding that sleeping in on the weekend 'doesn't repay the sleep debt'.
'Parents should remove "stimulants", such as TVs, computers and mobile phones from bedrooms,' advises Dr McCrindle.
Cutting down on caffeinated drinks during the day can also help, he says. 'Some of the biggest culprits, such as energy drinks, are very popular with teenagers.'