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Why Sitting For Long Periods Can Affect Teens' Mental Health


Too much sitting puts people at a higher risk of chronic illnesses like heart disease and obesity. Research backs that up. But a new study also suggests that when teenagers sit around for long periods of time, it can affect their mental health, too. NPR's Rhitu Chatterjee looked into it.

RHITU CHATTERJEE, BYLINE: Researchers in the United Kingdom have been following over 4,000 children since their birth, collecting data on their daily behaviors and health. Aaron Kandola is a graduate student at the University College London and an author of the new study published in The Lancet Psychiatry. He says scientists tracked the kids daily physical activity using wearable devices called accelerometers.

AARON KANDOLA: These are little, tiny devices that are worn on the body, and they record bodily movements. It's the same device that you might find in your mobile phone or in a Fitbit.

CHATTERJEE: And they track how much time someone spends being physically active each day. Kandola and his colleagues analyzed this data from when the children were 12, 14 and 16 years old. And they found that as these kids went through adolescence, they spent more time sitting.

KANDOLA: The daily amount of time that was spent sedentary increased from around seven hours, 10 minutes to about eight hours and 40 minutes.

CHATTERJEE: This extra hour and a half of sitting around, Kandola says, was linked to a higher risk of having symptoms of depression later in life.

KANDOLA: For every hour increase in sedentary time per day was associated with around an 8% to 11% increase in depression score at age 18.

CHATTERJEE: But the good news here, he says, is that increasing the amount of time spent doing physical activity by even an hour each day cuts that risk of depression by 10%. A two-hour increase cut the risk by 20%. Now, this doesn't have to involve going to the gym or playing sports; just moving around more, doing everyday things like walking at school or at home, running errands or even standing and talking to someone can make a difference. Psychologist Karmel Choi is a research fellow at Harvard University.

KARMEL CHOI: This is encouraging because light activity is low-hanging fruit. It's doable. It takes less effort. It's an easy alternative. And so it's more likely that young people can follow through on it.

CHATTERJEE: Choi, who wasn't involved in the new study, says since kids spend most of their days at school, schools can help ensure that teenagers move around more by doing simple things like...

CHOI: Have stretching breaks, whole standing classes or even being intentional about how classes are scheduled, say, at different ends of the hallways.

CHATTERJEE: And there are things parents can do, too.

CHOI: Getting teens engaged in house chores like washing the dishes or putting away the laundry, maybe setting up a standing desk for the computer for doing homework.

CHATTERJEE: Symptoms of depression often appear first during adolescence. So, Choi says, preventing depression in this critical period could have a lasting impact on people's mental health.

Rhitu Chatterjee, NPR News.

(SOUNDBITE OF MARCUS D'S "LIVE BETTER") Transcript provided by NPR, Copyright NPR.

Rhitu Chatterjee is a health correspondent with NPR, with a focus on mental health. In addition to writing about the latest developments in psychology and psychiatry, she reports on the prevalence of different mental illnesses and new developments in treatments.