The more you watch TV, the less healthy you will be as you grow older, Harvard study finds

Ditto for sitting in cars or at home doing something besides watching TV, such as reading, eating meals or paying bills.

For every additional two hours spent in front of the TV, the chance of meeting the researchers’ definition of healthy ageing dropped by 12 per cent. Photo: Shutterstock

Yet for every additional two hours spent in front of the TV, a person’s chance of meeting the researchers’ definition of healthy ageing declined by 12 per cent, according to their study, published in JAMA Network Open.

That does not bode well for the United States, where 62 per cent of adults between the ages of 20 and 64 say they watch TV for at least two hours a day, as do 84 per cent of senior citizens.

The findings are based on data from more than 45,000 women who took part in the Nurses Health Study. All of them were at least 50 years old and had no major chronic diseases in 1992, when they answered questions about their health and what they did all day.

For instance, the nurses were asked how much time they spent standing or walking around at work or at home. They were asked about various types of exercise, including jogging, swimming laps, playing tennis and doing yoga. They were asked if they mowed their own lawns.

You might not be surprised to learn that the most popular type of sitting was sitting while watching television. More than half of the women – 53 per cent – said they watched between six and 20 hours of TV a week. (The median among this group was around 15.4 hours per week.) Another 15 per cent of the women said they watched between 21 and 40 hours of TV each week, and 2 per cent watched even more.

The Harvard study links hours spent in front of the TV with a drop in health as we age. Photo: Shutterstock

Only 8.6 per cent of the women met all four of those criteria, which was what it took to achieve healthy ageing.

On the whole, the women who watched more TV tended to be older, were more likely to be smokers or drinkers, consumed more calories and had higher body mass index scores than women who watched less TV. The more devoted TV watchers were also more likely to have high blood pressure and high cholesterol.

Once the researchers accounted for these and a host of other differences, they found that the women who spent an hour or less each week sitting in front of the TV were the most likely to achieve healthy ageing.

Compared to them, women who watched TV for two to five hours per week were 9 per cent less likely to be healthy agers; those who watched for six to 20 hours per week were 19 per cent less likely; those who watched for 21 to 40 hours per week were 40 per cent less likely; and those who watched for at least 41 hours a week were 45 per cent less likely.

The researchers also found that replacing TV time with pretty much anything else – including sleep, for women who got no more than seven hours of sleep per night – would increase their odds of healthy ageing. The more vigorous the new activity, the bigger the boost.
Replacing time in front of the TV with vigorous exercise or physical activity is ideal, but even sleeping is preferable to sitting on the couch. Photo: Shutterstock

Although the actual percentage of women who succeeded in healthy ageing was low, the study authors estimated that another 61 per cent of the women could have joined that rarefied group if they had done four things:

The study did not show that excess TV time caused any of the nurses to miss out on healthy ageing, only that there was a significant inverse correlation between the two.

Still, there is good reason to suspect that their favourite sedentary behaviour bore at least some of the responsibility.

Previous studies have linked prolonged sitting – especially while watching television – to a variety of health problems, including diseases like breast cancer, colorectal cancer, type 2 diabetes, cardiovascular disease and early death. (That particular study found that compared to sitting for less than three hours a day, sitting for at least twice that long was associated with a 17 per cent increased risk of premature death for men and a 34 per cent increased risk of premature death for women.)

But the researchers from Harvard’s TH Chan School of Public Health have taken things a step further, said Dr I-Min Lee, an epidemiologist at Brigham & Women’s Hospital in Boston who studies how physical activity can prevent chronic diseases and extend life.

Dr I-Min Lee, an epidemiologist at Brigham & Women’s Hospital in Boston, studies how physical activity can prevent chronic diseases and extend life. Photo: Brigham & Women’s Hospital

“This study expands what we know because it looked at ‘healthy ageing’,” said Lee, who was not involved in the study. “‘Health’ is not just the absence of disease; it includes dimensions of physical and mental health, function and well-being.”

All of the study subjects were women, but the biological mechanisms are likely to apply to men as well, Lee said. Even so, it would be good to actually test this relationship in men, as well as in people from a wider range of racial and ethnic backgrounds, she said. (The group of women in the original Nurses Health Study was overwhelmingly white.)

The youngest of the Baby Boomers are now turning 60, and the proportion of the US population that is at least 65 is projected to increase from roughly 17 per cent today to nearly 21 per cent in 2050, according to the US Census Bureau.

“Population ageing is an important public health issue,” the study authors wrote, and strategies to promote healthy ageing “are urgently needed”.

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