Effects of insomnia on depression, fatigue and quality of life in youths

Abstract

Insomnia is the most common sleep problem affecting youths worldwide. Insomnia in youth is closely associated to a variety of negative consequences, including mood disturbances and impairments in daytime functioning. In particular, fatigue and lower quality of life are linked to impaired daytime functioning in youths. Yet, the effect of insomnia on fatigue level and quality of life were rarely examined in the youth population. Moreover, there is a high co-morbidity of insomnia and depression in youths but the optimal treatment approach to address this common comorbidity remained unclear. This thesis aimed to evaluate the impacts of youth insomnia on fatigue and quality of life, and to evaluate the efficacy of two cognitive behavioural approaches, i.e. cognitive behavioural therapy for insomnia (CBT-I) and cognitive behavioural therapy for depression (CBT-D), in treating youths with comorbid insomnia and depression. Study 1 was a cross-sectional study that involved a sample of university students (n=725). Participants completed a battery of questionnaires to assess their insomnia severity (as measured by Insomnia Severity Index), depressive symptoms (as measured by Depression Anxiety Stress Scales-Depression Scale), fatigue (as measured by Multidimensional Fatigue Inventory) and quality of life (as assessed by KIDSCREEN-27). The results indicated that 42.7% of the participants had insomnia symptoms, which were associated with depressive mood, fatigue and lower quality of life. In addition, fatigue was found to mediate the relationship between insomnia and depressive symptoms, and between insomnia and quality of life. Study 2 was a randomized controlled trial that examined the effects of group-based CBT-I and CBT-D on insomnia, depression, fatigue and quality of life in youths with comorbid insomnia and depression (n=112). Participants in both active treatment groups were found to show significant improvements in sleep, depression, fatigue and quality of life at post-treatment one-week and one-month follow-ups, as compared to the waitlist control group. Both groups achieved a high remission rate of overall clinical symptoms (insomnia and depression) at the one-month follow-up (CBT-D: 77.8% and CBT-I: 74.1%). The results suggested sleep-focused treatment is efficacious in comorbid insomnia and depression management in young people. Further studies with longer follow-up periods are needed to examine whether the beneficial effects of CBT-I on improving mood, fatigue and quality of life could sustain over time in youths.