Watching TV for three hours a day can be deadly – doubling your risk of dying early, warn researchers.
A new study from Spain adds to evidence that time spent in front of the box is potentially life-threatening.
Researchers believe too much sitting – as opposed to insufficient activity – may be a new risk factor for premature death and illness such as diabetes and heart disease.
Professor Miguel Martinez-Gonzalez, chair of the Department of Public Health at the University of Navarra in Pamplona, who led the study, said ‘Television viewing is a major sedentary behaviour and there is an increasing trend toward all types of sedentary behaviours.
‘Our findings are consistent with a range of previous studies where time spent watching television was linked to mortality.’
Researchers assessed 13, 284 young and healthy Spanish university graduates, average age 37, to investigate possible links between three types of sedentary behaviour and risk of death: television viewing time, computer time and driving time.
The participants were followed for around eight years, when there were 97 deaths, including 19 deaths from cardiovascular causes, 46 from cancer and 32 from other causes.
The risk of premature death was twofold higher for those watching three or more hours of TV a day compared to those watching one hour or less.
This twofold higher risk was also apparent after accounting for many other variables related to a higher risk of death, says a report published in the Journal of the American Heart Association.
Researchers found no significant association between the time spent using a computer or driving and higher risk of premature death from all causes.
Researchers said further studies are needed to determine the biological mechanisms that may be involved.
Prof Martinez-Gonzalez said ‘As the population ages, sedentary behaviours will become more prevalent, especially watching television, and this poses an additional burden on the increased health problems related to aging.
‘Our findings suggest adults may consider increasing their physical activity, avoid long sedentary periods, and reduce television watching to no longer than one to two hours each day’ he added.
In the UK, the average amount of time spent watching TV is four hours a day compared with five hours in the US.
Previous research found people who watch six hours of TV a day cut short their lifespan by five years compared with someone who watches no TV.
People who sit for longer have bigger waist sizes, and higher levels of cholesterol, blood sugar and triglycerides.
The average adult spends 90 per cent of their leisure time sitting down and less than half of adults meet World Health Organisation physical activity recommendations.
In the UK, adults are urged to do 150 minutes of activity a week to promote health.
Other work suggests sedentary behaviour is linked to obesity, high levels of bad blood fats and other heart disease risk factors, and more opportunities for grazing on junk foods.
US research earlier this year found young men who watch TV for just three hours a day have half the sperm count of men who rarely watch TV.