The study, led by the University of Southern Queensland’s Professor Stuart Biddle, also found longer sitting times could lead to a higher risk of poor quality of life.
Professor Biddle said the study, which was published in the Journal of Affective Disorders, was a significant step towards fully understanding the causes and effects of sedentary behaviour on mental health.
“While there is substantial evidence of the harmful effects of sitting on our physical health, much less research has assessed whether higher levels of sedentary behaviour is associated with higher levels of mental health problems,” said Professor Biddle, who was involved in developing the World Health Organisation’s latest guidelines on physical activity and sedentary behaviour.
“Our research suggests that total and prolonged sitting times are associated with a greater risk of depression and poorer quality of life.
“We hope these results make people sit up and take notice.”
The researchers looked at data from three studies, totalling more than 1500 adults.
They found adults with longer sitting times – total sitting (average of 9.2 hours per day) and, importantly, prolonged sitting (average of 4.9 hours per day in bouts of at least 30 minutes) – were 14 per cent more likely to be associated with higher levels of depression.
Professor Biddle said the strength of the research was the data, which was collected from research-grade wearable devices – thigh-mounted accelerometers – designed to measure time spent sitting/lying, standing and stepping.
“Previous research of this type has relied on self-reported sedentary behaviour, but we wanted to examine studies that used wearable devices because they have shown to be much more accurate,” he said.
“It meant we were able to look at the number of occasions each participant moved from sitting to standing during the trial, and calculate the amount of time they sat, stood and stepped.
“Our findings could help guide preventive interventions and personalised treatments, as well as inform future studies that are needed to address the growing mental health crisis.”
The study highlighted that physical activity could help prevent and reduce the risk of depression, but Professor Biddle said more work needed to be done in ambulatory adults to determine if more physical activity can offset the negative mental health impacts of sitting for long periods.
“Almost half of all Australians will experience mental health issues at some point of their lives,” Professor Biddle said.
“Given we spend an average of 39 hours per week doing sedentary activities, such as watching television, playing video games and using a computer, the more information we have about the links between sitting time and mental health, the better chance we have of delivering interventions that minimise the risks.
“The biggest problem is we have created environments that encourage us to sit more and move less.
“The challenge for us is to find easy ways to inject movement into our days, but sitting less is a good start. For those using wheelchairs, more movement is also essential.”
The study, ‘Device-assessed total and prolonged sitting time: associations with anxiety, depression, and health-related quality of life in adults’ can be read here.