If you need another reason to shut off the TV and get moving, this information just might do the trick. According to a recent study, low levels of exercise and watching a lot of television are each linked to a higher risk of depression compared to high levels of exercise and little TV viewing.
Researchers from Harvard School of Public Health used data from women taking part in the Nurses’ Health Study who had filled in questionnaires every two years from 1992 to 2000. They selected 49,821 who were did not suffer from depression in 1996.
The questionnaire data included information about physical activity (such as cycling, walking, running, swimming), which allowed the researchers to compile a figure for a total average number of minutes of physical activity per day. The participants had also been asked about their TV viewing habits in 1992, and from those responses the researchers calculated how many hours a week the participants spent watching TV. The investigators were able to determine which women developed clinical depression over the follow up (from 1996 to 2006) from their self reports of whether they had been diagnosed with such by a doctor or whether they were taking anti-depressants.
The authors of the study found that over the follow-up there were 6,505 cases of depression; women who exercised an average of 90 minutes a day or more had a 20% lower risk of depression compared to those who exercised an average of less than 10 minutes a day; and women who watched 21 hours or more of TV a week had a 13% higher risk of developing depression compared to women who watched 1 hour or less.
The researchers admit that one limitation of their study was the possibility that some of the women may already have been depressed when the study began in 1996 and were diagnosed later during the follow up, and this could have been why they exercised less. While previous studies have shown a clear link between higher levels of regular exercise and lower risk of depression, it was less clear before this study whether physical activity and television viewing were linked with clinical depression risk.
