Study details

For the study, researchers took data from more than 45,000 women who participated in the Nurses Health Study. All nurses were aged 50 or older in 1992 and were free of chronic illnesses.

In the original study, nurses answered questions about their sitting and standing habits — both at home and at work — as well questions about their overall health.

Over the course of 20 years or until some participants had died, researchers followed up with them on their time sitting at work, at home watching television, and the time they spent standing or walking.  

Overall, researchers found that the majority of the time the participants spent sitting — and for the longest durations — was while watching TV. More than half of the nurses (53%) said they watched between six and 20 hours of TV per week. An additional 15% of the nurses said they watched between 21 and 40 hours of TV each week, and 2% watched even more.

At the end of the study's 20-year duration, 41% of the living participants were still free of major health conditions like cancer, diabetes, heart failure, chronic obstructive pulmonary disease, and multiple sclerosis. Nearly half (44%) were in good mental health, over half (52%) had no memory impairments, and 16% had no physical impairments.

Discussion

According to Andrew Freeman, director of cardiovascular prevention and wellness at National Jewish Health, these study results aren't surprising, as many other studies show that sedentary lifestyles can negatively impact our health.

"Vegging out in front of the television, seems to always be associated with worse outcomes," he said. "Of course, it makes physiologic sense that human beings were never meant to sit in front of a screen all day long."

"When people sit in front of TV, it usually brings all these other comorbid activities, like eating junk food, TV dinners, failing to connect with others, and it even can interrupt sleep," he added.

Sedentary behavior also takes away opportunities to be physically active. "You're missing out on all that physical activity, which is truly an unbelievable way to reduce cardiovascular risk and blood pressure," Freeman said.

Freeman suggests that, for people working more than eight hours a day in an office, they should find creative ways to incorporate movement into their days. He suggests leveraging apps or tools that can help adults track their active time, as well as time they stared at a screen.

"Our take-home message is that replacing TV time with light physical activity, moderate-to-vigorous physical activity, and sleep (for participants with inadequate sleep) is beneficial to healthy aging," said senior study author Molin Wang, associate professor of medicine in the department of epidemiology at Harvard University's T.H. Chan School of Public Health.