Why 5 or More Hours of TV Daily Is Bad for You

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Bad news for couch potatoes: Spending hours parked in front of the TV may increase the risk of dying from a blood clot in the lung, a new study from Japan finds.

People in the study who watched TV for 5 hours or more each day were 2.5 times more likely to die during the study period from a blood clot in the lung, also called a pulmonary embolism, compared with people who watched TV for less than 2.5 hours a day.

A pulmonary embolism can be deadly. It occurs when a blood clot that formed somewhere else in the body (typically in the leg or pelvis) travels through the blood vessels to the lungs. There, it becomes trapped in a smaller blood vessel, which can lead to heart failure.

In the study, the researchers looked at data on more than 86,000 adults who were taking part in an ongoing study called the Japanese Collaborative Cohort Study. The people in the study reported how many hours they spent watching TV daily (choosing from less than 2.5 hours, between 2.5 and 4.9 hours, and 5 or more hours), as well as information about their body mass index, health history, physical activity levels and whether they smoked. [9 Odd Ways Your Tech Devices May Injure You]

Over the 19-year follow-up period, 59 people died of a pulmonary embolism, according to the study, published today (July 25) in the journal Circulation. The researchers found that, compared with people who watched less than 2.5 hours of TV a day, there was a 70 percent increased risk of dying from a pulmonary embolism in people who watched between 2.5 and 5 hours. In addition, for every 2 hours spent watching television, the risk of dying from a pulmonary embolism increased 40 percent, according to the study.

The researchers noted that the participants reported their television-viewing habits in the late 1980s,  but people's viewing habits have changed significantly since then.

In particular, binge-watching, or watching a great many episodes of one show over a short period of time, has become popular, Dr. Toru Shirakawa, a public health researcher at Osaka University Graduate School of Medicine and the lead author of the study, said in a statement. "This popularity may reflect a rapidly growing habit," he said.

In addition to binge-watching, time spent sitting and using smartphones and personal computers also needs to be studied, the researchers wrote.  

In Japan, pulmonary embolism occurs at a lower rate than it does in Western countries, Dr. Hiroyasu Iso, a professor of public health, also at Osaka University, and a co-author of the study, said in a statement. But Japanese people may be adopting increasingly inactive lifestyles, which may raise their risk of pulmonary embolism, he said. 

Blood clots can form during long stretches of inactivity, because blood flow slows down, which can allow the blood to pool, giving it a chance to clot.

There are some simple steps a person can do to reduce their risk of blood clots, Iso said. 

To get blood flowing, "After an hour or so, stand up, stretch, walk around, or while you're watching TV, tense and relax your leg muscles for 5 minutes," Iso said. This advice to similar to what doctors often tell travelers embarking on long flights, he added. Drinking water may also help, and for people who are overweight, losing weight may reduce the risk, he said. 

This is not the first study to suggest there is a link between TV-watching and a person's risk of an earlier death. In 2014, for example, a study from Spain found that people who watched 3 or more hours of TV a day were more likely to die during the eight-year study period.

Originally published on Live Science.

Sara G. Miller
Staff Writer
Sara is a staff writer for Live Science, covering health. She grew up outside of Philadelphia and studied biology at Hamilton College in upstate New York. When she's not writing, she can be found at the library, checking out a big stack of books.