Prospective associations between joint categories of physical activity and insomnia symptoms with onset of poor mental health in a population-based cohort

Background:Physical inactivity and insomnia symptoms are independently associated with increased risk of depression and anxiety;however,few studies jointly examine these risk factors.This study aimed to prospectively examine the joint association of physical activity(PA)and insomnia symptoms with onset of poor mental health in adults.Methods:Participants from the 2013 to 2018 annnual waves of the Household Income and Labour Dynamics in Australia panel study who had good mental health(Mental Health Inventory-5>54)in 2013,and who completed at least 1 follow-up survey(2014-2018),were included(n=10,977).Poor mental health(Mental Health Inventory-5≤54)was assessed annually.Baseline(2013)PA was classified as high/moderate/low,and insomnia symptoms(i.e.,trouble sleeping)were classified as no insomnia symptoms/insomnia symptoms,with 6 mutually exclusive PAinsomnia symptom groups derived.Associations of PA-insomnia symptom groups with onset of poor mental health were examined using discrete-time proportional-hazards logit-hazard models.Results:There were 2322 new cases of poor mental health(21.2%).Relative to the high PA/no insomnia symptoms group,there were higher odds(odds ratio and 95%confidence interval(95%CI))of poor mental health among the high PA/insomnia symptoms(OR=1.87,95%CI:1.57-2.23),moderate PA/insomnia symptoms(OR=1.93,95%CI:1.61-2.31),low PA/insomnia symptoms(OR=2.33,95%CI:1.96-2.78),and low PA/no insomnia symptoms(OR=1.14,95%CI:1.01-1.29)groups.Any level of PA combined with insomnia symptoms was associated with increased odds of poor mental health,with the odds increasing as PA decreased.Conclusion:The se findings highlight the potential benefit of interventions targeting both PA and insomnia symptoms for promoting mental health.