Binge watching telly increases the risk of dying from a blood clot on the lung by almost 70 per cent, according to new research.
Watching for more than five hours a day may be as bad as a long haul flight for increasing the chances of suffering a blood clot.
And researchers believe new technology such as tablets and and laptops may increase the risks.
Anybody planning to spend a day watching a box set should take precautions, including getting up and walking around for five minutes every hour and making sure they drink enough water.
A lung blood clot – known medically as a pulmonary embolism – usually begins as a clot in the leg or pelvis as a result of inactivity and slowed blood flow.
If the clot breaks free, it can travel to the lung and become lodged in a small blood vessel, where it is particularly dangerous.
Researchers questioned 86,024 people aged between 40-79 in Japan between 1988 and 1990 about their watching habits.
Over the next 19 years 59 died of a pulmonary embolism, according to the study published in the American Heart Association’s journal Circulation.
Compared to participants who watched TV less than 2.5 hours each day, deaths from a pulmonary embolism increased by 70 percent among those who watched TV from 2.5 to 4.9 hours.
For every additional two hours of additional watching it increased by another 40 per cent with the 2.5 times increase in the chances of a clot among those who watched TV 5 or more hours.
Dr Hiroyasu Iso, M.D., Ph.D., professor of public health at Osaka University Graduate School of Medicine, said: “Pulmonary embolism occurs at a lower rate in Japan than it does in Western countries, but it may be on the rise.
“The Japanese people are increasingly adopting sedentary lifestyles, which we believe is putting them at increased risk.”
The authors suggested that risk is likely to be greater than the findings suggest.
Deaths from pulmonary embolism are believed to be underreported because diagnosis is difficult.
The most common symptoms of pulmonary embolism – chest pain and shortness of breath – are the same as other life-threatening conditions, and diagnosis requires imaging that many hospitals are not equipped to provide.
Researchers accounted for several factors that might have influenced findings, including obesity, diabetes, cigarette smoking and hypertension. After the number of hours spent watching TV, obesity appeared to have the next strongest link to pulmonary embolism.
Dr Toru Shirakawa, the lead auther and a research fellow in public health at Osaka University Graduate School of Medicine, said the findings may be particularly relevant people in the west because studies suggest they watch more tell than the Japanese.
“Nowadays, with online video streaming, the term ‘binge-watching’ to describe viewing multiple episodes of television programs in one sitting has become popular,” Shirakawa said. “This popularity may reflect a rapidly growing habit.”
Authors said people who watch a lot of TV can take several easy steps to reduce their risk of developing blood clots in their legs that may then move to their lungs.
“After an hour or so, stand up, stretch, walk around, or while you’re watching TV, tense and relax your leg muscles for 5 minutes,” said Iso, noting this advice is similar to that given to travelers on long plane flights.
He added that drinking water may also help and, in the long run, shedding pounds if overweight is likely to reduce risk.
The study recorded participants’ viewing habits before computers, tablets and smartphones became popular sources of information and entertainment.
The researchers believe more work needs to be done on the increased risk caused by new technologies such as phones, tablets and laptops.