Group-based cognitive behavioural therapy and bright light therapy in youths with insomnia and evening chronotype: Interim analysis of a randomised controlled trial

Forrest Tin Wai Cheung, Ngan-yin Chan, Joey Wing Yan Chan, Jihui Zhang, Albert Martin Li, Colin A. Espie, Michael Gradisar, Yun-Kwok Wing, Shirley Xin Li

Abstract

Introduction: Insomnia and eveningness are prevalent and often comorbid in youths. Whilst cognitive behavioural therapy for insomnia (CBT-I) is a promising intervention in adults, its effectiveness in addressing comorbid insomnia and circadian issues in youths remained unclear. In addition, it remained unclear whether addition of bright light therapy (BLT) (being effective in shifting circadian phase) and CBT-I will further improve sleep and circadian outcomes in youths. This study examined the efficacy of CBT-I and CBT-I plus BLT in improving insomnia symptoms, mood symptoms, daytime functioning (e.g., sleepiness, fatigue, cognitive functioning) and circadian measures compared to a waitlist control group.

Materials and Methods: This is an assessor-blind, parallel-group, randomised controlled trial. 114 participants (age: 19.8 ± 3.3, 53.5% female) with comorbid insomnia with significant impairments/distress and eveningness were recruited. Participants were randomised into one of the three groups: CBT-I with active BLT (CBTI+BLT), CBT-I with placebo BLT (CBTI-BLT), and waitlist control. The intervention comprised six-week group-based CBT-I with BLT starting from the second week. Assessments were completed at baseline and post-treatment, and the two intervention groups completed a follow-up assessment at 1-month post-treatment. The primary outcomes included changes in insomnia symptoms as measured by the insomnia severity index (ISI), circadian preference as measured by the morningness-eveningness questionnaire (MEQ), and the midpoint of sleep derived from the Munich chronotype questionnaire (MCTQ). Secondary outcomes included sleep parameters measured by sleep diary and actigraphy, and measures of mood symptoms and daytime functioning. Analyses of outcome measures were conducted using multilevel modelling (MLM) following the intention-to-treat principle.

Results: An MLM comparison between the three groups showed a significant treatmenttime interaction effect on insomnia severity (F(2, 99.63) = 8.36, p = .001), where both intervention groups had significant improvements in insomnia severity as measured by ISI compared to WL. The treatmenttime interaction effect was significant for the midpoint of sleep (F(2, 100.11) = 4.47, p = .01) but insignificant for MEQ scores (F(2, 98.59) = 1.60, p = .21). Post-hoc analyses showed only the CBTI+BLT group showed significant advancement of the circadian phase as measured by MCTQ (p = .004, d = 0.69). Regarding secondary outcomes, significant treatment*time interactions between the three groups were found in self-report sleep quality, clinician-rated mood measures, and measures on daytime functioning. MLM results showed similar improvement of treatment effects between CBTI+BLT and CBTI-BLT on the primary and secondary outcomes at post-treatment and 1-month follow-up.

Conclusion: The current study showed that CBT-I effectively improves insomnia severity, depressive symptoms, and daytime functioning in youths with insomnia and eveningness. CBT-I with adjunct BLT additionally advanced the circadian rhythm. Future research could include objective measures of sleep and circadian parameters, such as polysomnography and utilising circadian biomarkers. Lastly, the potential moderating effects of circadian rhythm on treatment outcomes of CBT-I should be examined.

Recommended citation: Cheung, F. T. W., Chan, N. Y., Chan, J. W. Y., Zhang, J., Li, A. M., Espie, C. A., ... & Li, S. X. (2024). Group-based cognitive behavioural therapy and bright light therapy in youths with insomnia and evening chronotype: interim analysis of a randomised controlled trial. Sleep Medicine, 115, S178-S179.
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