The role of locus of control in the relationship between insomnia and anxiety symptoms in youths

Abstract

Youth insomnia is highly prevalent worldwide. Insomnia, if left untreated, may bring adverse impacts to one’s health, functioning and quality of life. Moreover, insomnia and anxiety problems often co-occur in youths. Previous studies have examined various factors contributing to the relationship between insomnia and anxiety, yet limited research has investigated the role of locus of control, i.e. the tendency of a person to attribute an event to external forces or his or her own behaviours along a continuum from more externalized to more internalized. In addition, while Cognitive Behavioural Therapy for Insomnia (CBT-I) is considered as the first-line treatment for insomnia, it remains unclear whether CBT-I is effective in addressing the comorbidity of insomnia and anxiety in youth and its underlying mechanism. Therefore, this thesis aimed to evaluate the relationship between locus of control, insomnia and anxiety in youth, to assess the efficacy of CBT-I in treating youths with comorbid insomnia and anxiety, and to investigate the potential mediating role of changes in insomnia severity and locus of control on the impact of CBT-I in improving anxiety symptoms. Study 1 was a cross-sectional study that examined the mediating effects of locus of control in the association between insomnia and anxiety in a community-based sample of youths (n=399). Participants completed a battery of self-reported questionnaires to assess their insomnia severity (as measured by Insomnia Severity Index), anxiety symptoms (as measured by Depression Anxiety Stress Scales-Anxiety Scale), and locus of control (as measured by Locus of Control Scale). The results indicated that locus of control partially mediated the relationship between insomnia and anxiety. Study 2 was a pilot study with a randomised controlled design to investigate the efficacy of CBT-I on youths with insomnia and anxiety symptoms in Hong Kong (n=57). Comparing to the waitlist control group, significant improvement in insomnia severity and anxiety symptoms were found in participants in the CBT-I group. However, no significant difference was found in locus of control between the two groups. The results provided preliminary evidence on the effectiveness of CBT-I in managing comorbid insomnia and anxiety in Hong Kong youths. Future studies with greater sample size, incorporation of objective measures and follow-up assessment may further enhance our understanding on the relationship between insomnia, anxiety and locus of control in the youth population.