Get off the couch; Long periods watching TV can lead to blood clots
Watching TV for long periods of time puts people at risk of deadly blood clots, experts have warned.
Sitting in front of the TV for five or more hours on average per day leads to twice the risk of fatal pulmonary embolism as watching less than two and a half hours per day.
The 18-year study on more than 86,000 people found a level of risk normally associated with flying.
Toru Shirakawa, public health research fellow in the Department of Social Medicine at Osaka University in Japan, who led the research, said people should stand up occasionally and drink water during programmes.
Presenting his findings at the European Society of Cardiology conference in London, he said: "We showed that prolonged television viewing may be a risky behaviour for death from pulmonary embolism.
"Leg immobility during television viewing may in part explain the finding."
He said people should "take a break, stand up, and walk around".
"Drinking water for preventing dehydration is also important."
Mr Shirakawa said prolonged use of computer games had also been linked to clots but no research had so far made a link with smartphones.
"The link between prolonged sitting and pulmonary embolism was first reported among air raid shelter users in London during the Second World War," he said.
"Nowadays, a long haul flight in an economy class seat is a well known cause of pulmonary embolism that is called economy class syndrome.
"Pulmonary embolism is a serious, sometimes fatal, lung-related vascular disease characterised by sudden onset of symptoms such as chest pain or difficulty breathing.
"The disease is caused by obstruction of the pulmonary arteries by blood clots, generally formed in the leg vessels."
The research looked at 36,007 men and 50,017 women aged 40 to 79.
They reported how much television they watched each day and were then followed for 18 years.
During the course of the study, there were 59 deaths from pulmonary embolism.
After adjusting for other factors that might influence the results, the experts found people had twice the risk of a clot if they watched five or more hours, rising to a six-fold risk if they were under 60.