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Binge-watching your favourite series isn’t so good for your circulation, a new review of the research suggests. The study found that people who regularly watched TV four or more hours a day were more likely to develop a blood clotting condition that can lead to serious health problems and even death. What’s more, this increased risk was seen independently of other important factors like a person’s level of physical activity.
The condition is known as venous thromboembolism, or VTE, and is caused by blood clots that form in our veins. The most common form of VTE is deep vein thrombosis (DVT), which is when these clots get stuck in the deepest veins of our body, usually along our legs or pelvis but sometimes in our arms.
DVT clots can cause acute swelling and pain when they happen, though many people may not experience any symptoms. These blockages can then damage the valves in our veins, especially if not treated early, leading to long-term complications like chronic pain, swelling, and ulcers. And the clots can also get dislodged from their original site and clog up the arteries of our lungs, where they can cause a life-threatening condition called pulmonary embolism. It’s estimated that close to a million people in the U.S. may develop DVT every year, and that up to 100,000 Americans die annually from the combination of DVT and pulmonary embolism.
Common risk factors for VTE include age, injury to the veins, and existing health conditions like heart disease. But it’s also known that simply being in one place for too long can increase that risk, too, which is often seen when people are confined to a hospital bed from severe illness. So it’s not exactly a surprise that some researchers have wondered whether long sessions in front of the TV could also be a potential contributor to VTE.
Lead author Setor Kunutsor of the University of Bristol and his team already study how to best prevent cardiovascular diseases like VTE. So they wanted to better understand the link between TV-watching and VTE by reviewing and collectively analysing the few studies that have specifically looked at the topic.
They analysed data from three earlier observational studies involving more than 130,000 participants 40 years old and above who hadn’t been diagnosed with VTE at the start of the study. Their health was tracked for over several years, sometimes for up to 20 years, and they were also asked about their lifestyle habits, including their TV-viewing time.
Overall, about 1,000 people were diagnosed with VTE at some point during the study period. Those who fit the criteria of being prolonged TV-watchers — four or more hours a day on average — were 35% more likely to develop VTE than those who never or seldom watched TV. The team’s findings were published Wednesday in the European Journal of Preventive Cardiology.
The authors are careful to note that this sort of research can only show a correlation between TV-watching and VTE, not prove that the former helps cause the latter. And because there have only been a few studies on this association, the authors say further research is needed to clarify just how harmful extended TV watching could be for our veins. But the link was found even when other factors that could raise or lower the risk of VTE were taken into account, further supporting the idea that binge-watching by itself is a unique hazard.
“The association was independent of age, sex, body mass index and physical activity, which are strongly related to the risk of VTE,” Kunutsor told Gizmodo in an email. “This means that the relationship we observed between TV viewing and VTE risk cannot be explained by age, sex, body mass index and physical activity. The relationship does not depend on these factors.”
Long periods of sedentary behaviour are obviously the strongest plausible explanation for why binge-watching could increase VTE risk. And it’s already known that TV watching is linked to heart disease for this same reason. But there’s also the possibility that people’s diets while binging TV are likely to be unhealthier in general, leading to other conditions like high blood pressure that further raise that risk.
While the relationship between TV and blood clotting risk may exist even for people who stay in shape, that doesn’t mean physical activity is worthless. Kunutsor and his team have previously found that exercise does have a protective effect in preventing VTE, regardless of body mass index. And even if you’re committed to your marathons of addictive shows, you can probably still lower your risk of VTE by taking time every so often to remain active.
“If you want to binge on TV viewing, take regular breaks in-between. You can stand and stretch every 30 minutes,” Kunutsor said, noting that the same advice goes for those who sit at work for long hours every day.
If you’re already physically active but still have to sit at work and/or love to binge, he added, “now is the time to increase your physical activity levels, as there is evidence showing that higher volumes of moderate and vigorous activity can reduce, or even eliminate the adverse risks associated with sedentary behaviour.”