Serial mediation effect of physical activity and sleep quality between dietary behaviour and depression symptoms: A nationwide cross-sectional survey

Substantial studies have revealed the potential mechanisms underlying the link between dietary behaviour and depression symptoms. This study investigated the relationship between depression symptoms and dietary behaviour, physical activity, and sleep quality in a nationwide sample of Chinese residents. A total of 18 819 Chinese Residents completed the dietary behaviour, patient health questionnaire, international physical activity questionnaire, and Pittsburgh sleep quality index. We used the Hayes' serial mediation model to investigate the correlation between the variables. Among the participants, 85.5% were aged between 18 and 59, 41.2% were male, and 73.8% were urban residents. There is a negative correlation between dietary behaviour and physical activity (r = -0.038, P