June 26, 2014
News Review From Harvard Medical School -- Study: TV May Boost Risk of Early Death
Spending a lot of time in front of the TV could increase your risk of early death, a new study suggests. The study found this link only for TV watching. There was no increase in death risk for other things that involve sitting -- computer use and driving. The study included more than 13,000 healthy young adults. They were highly educated, slim and active. Their average age was 37. People filled out questionnaires about their activities. In the next 8 years, 97 died. There were 19 deaths from heart disease, 46 from cancer and 32 from other causes. For every 2 extra hours daily spent watching TV, the risk of death from heart disease rose 44%. Risk rose 21% for cancer and 55% for other causes. Researchers tried to account for other factors that might have caused the link. They excluded people who died in the first year of the study. They also adjusted numbers to account for people's diet, smoking status, age, sex and weight. The link persisted. But this does not prove that TV watching actually caused the early death. The Journal of the American Heart Association published the study. HealthDay News wrote about it June 25.
By Robert H. Shmerling, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
You've probably heard this before: exercise is good for you.
The converse is also true: too much inactivity is bad for you. But are some sedentary activities worse than others? For example, is watching a lot of television worse for your health than staring at a computer screen for long hours?
That's just what researchers in Spain set out to answer. The Journal of the American Heart Association published the results this week. The study enrolled more than 13,000 young and middle-aged adults. Their average age was 37. People were asked about their how much time they spent watching TV, using a computer and driving.
When considering rates of death, it seemed that watching a lot of TV was worse than using a computer or driving. Eight years after the first survey:
- People who reported watching 3 or more hours of TV each day had twice the risk of death as those watching less than an hour of TV each day.
- People who spent the most time driving or using a computer did not have higher rates of death than those spending less time at these activities.
- The higher rate of death among heavy TV viewers did not seem related to less physical activity, heavier weight (higher body mass index) or higher rates of smoking.
Keep in mind that a study of this sort can only show a link between watching more TV and having a higher risk of death. It cannot prove that watching TV actually caused the higher risk of death.
Also remember that people were asked about their activities at only one point in time. In later years, the amount of time spent sitting still or exercising could have changed dramatically.
This study included relatively young adults whose overall death rate was quite low. Less than 1% of study subjects died during the follow-up period. It is challenging to sort out how particular activities affect the risk of death among such a small sample.
Finally, this study accounted for some factors (such as smoking) but not others that could have affected the results. The authors did not account for family history, cholesterol levels and blood pressure, among others. It's possible that TV watchers, for example, had higher blood pressure. Each of these factors could introduce significant error into the study's conclusions.
Still, the findings are intriguing -- and hard to ignore. Whether or not watching TV contributes to the early deaths of young and middle-aged adults, previous research is compelling. We know that getting regular exercise and sitting still less are important ways to improve your health and perhaps prolong your life.
What Changes Can I Make Now?
The authors of this study suggest limiting TV to "no longer than one to two hours each day." But I think it's far more complicated than that. The impact of reducing your TV watching from three to two hours a day would probably be quite small. And the benefits you get from cutting back on TV will depend at last in part on what you do with that time instead.
Most people cannot (and would not want to) completely eliminate inactivity from their lives. But you can make changes to increase your chances of living a long, healthy life. Here's what you can do:
- Exercise regularly. The American Heart Association suggests:
- Aerobic exercise for at least two and a half hours a week (or half that if it's high intensity)
- Muscle strengthening two or more days each week
- Don't smoke. If you smoke, quitting is the biggest thing you can do to improve your health.
- Maintain a healthy weight.
- Keep your blood pressure, cholesterol levels and blood sugar in a good range.
- Get screened for cancer and other diseases, and get vaccinated as recommended by your doctor.
Let your doctor know about any symptoms you are having. "Toughing it out" or wishing symptoms away is often not the best strategy.
What Can I Expect Looking to the Future?
The possibility that watching TV increases the risk of early death is not just intriguing -- it's worrisome as well. I'm all for encouraging less TV. But it's not clear to me why watching too much TV can double your risk of early death while equal or longer hours of computer work does not. And what conditions actually cause the early deaths of heavy TV watchers? Is it heart disease, stroke, cancer or something else? This study was too small to provide definite answers.
We need more research to confirm the findings of this latest research. But we also need studies to answer why and how watching TV might shorten a person's lifespan.
It's possible that in the future, as TV becomes more interactive, we might even figure out a way to watch our favorite shows with less inactivity -- and less risk.