Humans are made to move. Even just a century ago, few people spent their entire workday just sitting at a desk. Passive entertainment, too, is a relatively new innovation. Televisions have been widespread for barely 60 years. Radios, for less than a century. Books, for perhaps half a millennium. Sure, music and theater have existed for longer than that, but attending a live performance still involved trudging to the amphitheater or town square, sitting or standing on uncomfortable benches, and then making the same journey back home. And more people were likely to participate in making the music or plays when they couldn’t be recorded and electromagnetically transmitted through the air. Out of the hundreds of thousands of years Homo sapiens has existed, we’ve been intensely physically active for all but a few of them.
So clearly moving around is an important part of being human. When we don’t move our muscles quickly atrophy, and life-sapping deposits of fat build up around our vital organs. When we lose physical fitness we live shorter, disease-ridden lives.
To address this problem, many people living a modern lifestyle have adopted a routine much like my own. I get up at 6 a.m., often in the darkness, don my running gear and my MP3 player, and head outside for a 40-minute run. I hope my daily exercise routine, along with a few physical chores and perhaps a pickup soccer game on the weekend, will counteract the long hours I spend sitting in front of a computer screen during the day, or the television at night.
Photo courtesy of Gildas Fablet
Travis Saunders, a PhD student at the University of Ottawa who studies the impact of sedentary lifestyles, questions whether a little exercise can make up for hours of inactivity. He refers to a study led by G.F. Dunton of the University of Southern California and published in October in the International Journal of Obesity. The researchers conducted a phone survey of 10,000 Americans who ranged from normal weight to obese. As you might expect, people who engaged in a lot of physical activity tended to weigh less than those who did not.
But when the researchers considered how much time these individuals spent watching TV and movies, a different pattern emerged. No matter how much TV they watched, if they didn’t exercise, they had high BMIs (body mass index—a measure of obesity). But even among people who exercised more than an hour a day, those watching more than an hour of TV per day had significantly higher BMIs than those who did not. In fact, for respondents who watched more than an hour of TV, whether or not they exercised no longer predicted BMI.
Does this mean that watching TV and movies makes you overweight, regardless of how much exercise you get? Not necessarily—this is just a correlation, not a controlled experiment. It could be that some other factor is responsible. It might be that people with higher BMIs just like TV more. Or that they are eating and drinking more while they watch TV, compared to other activities.
But British science writer Christian Jarrett points to a controlled study that shows how TV-watching begins to affect physical activity starting at a very young age. In a study published last year in Child Development, a team led by Marie Evans Schmidt found that background TV has significant effects on toddlers’ play.
Fifty children, aged one through three, played by themselves in a room while a parent sat nearby reading magazines. Half the time (either at the beginning or end of the session), an episode of the game show Jeopardy! was playing in the background. The researchers videotaped the kids’ playing behavior and found that play episodes and focused attention were shorter while the TV show was on, even though no one was actively watching the show. Over a lifetime, this might mean that these kids are less able to focus on tasks—meaning that, even if they do exercise each day, they’re less likely to do so rigorously enough to burn excess calories. Other studies have shown that young kids who exhibit less-focused play episodes develop behavioral problems later on. Overall, while much more work still needs to be done, there’s considerable evidence that TV-watching may lead to passivity, which in turn leads to poorer health.
With all the negative impacts of TV, it might make you wonder whether TV offers any benefits at all. The pseudonymous neuroscience blogger “Neurocritic” found one study showing a benefit of television: People say they’re less lonely when they watch. As with the Dunton study, this is just a self-reported correlation, but if TV really makes people less lonely, that’s inarguably a plus.
But there may be more tangible benefits to TV, especially in developing nations. Daniel Hawes, a PhD candidate in applied at the University of Minnesota, discusses a study of a thousand villages in Tamil Nadu, India. The researchers found that shortly after the introduction of TV into a village, the standing of women improved dramatically. Villagers were more likely to say it was wrong for a husband to beat his wife, and women had greater autonomy and lower rates of pregnancy.
This makes some sense—in the US, the women’s liberation movement of the 1960s and 70s followed shortly after the nation-wide explosion of television ownership in the 1950s. It’s quite conceivable that TV’s power to induce social change—by giving people more access to information—is universal.
Paradoxically, while TV may be harmful to an individual’s mental and physical well-being, on the aggregate it could be beneficial to society. Perhaps, as with so many other things, the best advice might be to watch TV—but only in moderation. For more on the impact of TV and other technologies, visit ResearchBlogging.org.
Originally published December 23, 2009