If adults spent no more than two hours watching television each day, they could minimise their exposure to the health risks associated with the sedentary activity of watching TV, according to a new UK study published this week.
The research, led by the University of Glasgow and published in 'Mayo Clinic Proceedings', studied data to find that the majority of health risks associated with too much TV time could be reduced if people limited their viewing time to two hours a day, or less. The researchers found that the lowest overall health risks from diseases including cancers and cardiovascular disease were associated with viewing TV for two hours or less per day.
“This study adds more weight to the evidence that more time spent watching TV is likely to be detrimental to health,” said Dr Hamish Foster from the University of Glasgow's Institute of Health and Wellbeing, who led the study.
“Our study suggests limiting TV time could delay or prevent a lot of adverse health. However, there is still more work to be done before we can make firm TV time recommendations,” he said.
Further analysis as part of the study, entitled 'Understanding how much TV is too much: A non-linear analysis of the association between television viewing time and adverse health outcomes', estimated that 6 per cent of all-deaths and 8 per cent of cardiovascular deaths were attributable to TV time. They also showed that potentially, if all participants limited TV time to two hours a day, 5.62 per cent of all deaths and 7.97 per cent of deaths due to cardiovascular disease could have been prevented or delayed.
“TV time is just one of a number of potentially sedentary behaviours, which also includes screen time watching videos on your phone, which may all contribute to adverse health outcomes. Also, there are many other contributory factors, such as unhealthy snacking and lower socioeconomic status, that are also strongly associated with both TV time and poor health outcomes. Further research is needed to understand all these factors and inform future advice and guidelines,” added Dr Foster.
The researchers also looked at the potential benefits of substituting TV time with healthier activities such as walking. They found that those people who would benefit most from replacing longer periods of TV time with more time spent doing healthier activities, are those who currently only spend very small amounts of their day doing those healthier activities.
Current physical activity guidelines in UK encourage 150 minutes of moderate physical activity or 75 minutes of vigorous activity a week. On the other hand, current sedentary guidelines lack specific advice, and only suggest that people limit the time they spend sitting. There is currently no recommendation as to what might be a low risk amount of time to spend sitting watching TV each day.
In order to understand the risks, researchers examined lifestyle and demographic data from 490,966 UK Biobank participants aged 37-73 years, who were recruited between 2006-2010. Participants were followed up until 2016-2018 and their data was linked to national routine death and disease registries.
In order to reduce the chance of the results being due to reverse causality (where poor health leads to increased TV time) participants with non-communicable disease, cardiovascular disease and cancer were excluded. Similarly, the researchers excluded all those with an adverse health event within two years of recruitment.
