Network structure of insomnia and depressive symptoms among shift workers in China.

A bidirectional relationship between insomnia and depression has been observed. However, few studies have used network analysis to explore the interaction patterns in that association at the symptom level. This study aimed to estimate network structures of insomnia and depressive symptoms among shift workers, as well as to compare the differences in network properties between individuals without and with insomnia symptoms and/or at risk of depression. A total of 1883 shift workers were included in our study. Insomnia symptoms were evaluated by three items based on the criteria of the Diagnostic and Statistical Manual of Mental Disorders, and depressive symptoms were assessed by the Center for Epidemiologic Studies Depression Scale. Network analyses were used for the statistical analysis. "Difficulty initiating sleep", "Hard to get started", and "Depressed mood" with higher expected influence (EI) values were identified as the most central symptoms within the insomnia-depressive networks among shift workers. The significant differences between individuals without and with insomnia symptoms and/or at risk of depression were observed in symptoms of "Difficulty initiating sleep" and "Hard to get started". "Depressed mood", "Difficulty initiating sleep", or "Hard to get started" were the most key symptoms that trigger and sustain the structure of insomnia and depressive symptom among shift workers. Hence, timely intervention for the above three symptoms in future research or clinical practice (e.g., cognitive behavioral therapy for insomnia) may be crucial in alleviating insomnia and depressive symptoms among shift workers.