Spending too much time watching TV can be injurious to health. A new study done by the University of Glasgow and published in BMC Medicine reveals a link between higher risk of mortality and cardiovascular disease. The effect was more among those with low fitness, low muscle strength or physical activity levels. Previous studies linked increased screen time with bowel cancer for men as well as diabetes, obesity and a weak heart.
Discretionary screen time, time spent watching TV or looking at a computer screen during leisure time, is an important contributor to overall sedentary behaviour, which is associated with higher risk of mortality and cardiovascular disease. This is the largest single study to focus on this area. The researchers looked at 3,90,089 participants from the UK Biobank and analysed the amount of discretionary screen time.
In contrast, the potential adverse associations of high levels of discretionary screen time were much smaller in those who had the highest levels of fitness and grip strength. Professor Jason Gill, one of the lead authors of the study, said: “Our study shows that the risks associated with sedentary behaviour may not be the same for everyone, with the association between leisure time screen use and adverse health outcomes being strongest in those with low levels of physical activity, fitness or strength.”
The researchers also found that higher levels of screen time were associated with a higher risk of all-cause mortality, as well as a higher risk of both heart disease and cancer. The findings were independent of physical activity, grip strength, BMI, smoking, diet and other major confounding factors, including socio-economic status.