Efficacy of CBT-I With Adjuvant Melatonin in Older Adults Chronic Insomnia

This randomized, double-blind, placebo-controlled trial examines whether cognitive behavioural therapy for insomnia (CBT-I) with or without adjunct melatonin improves sleep and circadian outcomes as well as daytime functioning in older adults with chronic insomnia.

Eligible participants (aged ≥60 years, meeting DSM-5 criteria for insomnia disorder) will be recruited and randomly assigned to one of the three parallel groups: (1) CBT-I combined with nightly melatonin, (2) CBT-I with nightly placebo, or (3) sleep-health psychoeducation with nightly placebo. All interventions involve four weekly 90-minute group sessions (6-8 participants per group) conducted in person. Melatonin (3 mg immediate-release) or a matched placebo will be taken 30 minutes before habitual bedtime for four weeks.

Assessments will be conducted at baseline, mid-treatment (week 2, for the primary outcome only), and post-treatment (week 4) for all participants, and additionally at three-month and six-month follow-ups for participants in the two CBT-I groups. Data collection includes validated questionnaires on sleep, circadian, mood, fatigue, and quality of life, as well as computerized cognitive tasks to assess domains such as attention, working memory, and executive function. Objective sleep and circadian parameters will be measured by actigraphy for seven consecutive nights, along with a daily sleep diary. Participants will also complete polysomnography (PSG) for objective sleep assessment. To index circadian timing, a subset of participants will collect saliva samples (about 1 mL each) every 30 minutes under dim-light conditions in the evening to estimate dim-light melatonin onset (DLMO).

The primary outcome is the change in self-reported insomnia severity from baseline to post-treatment. Secondary outcomes include resumption and treatment response of insomnia, clinical symptom severity, objective and subjective sleep- and circadian-related outcomes, mood, daytime functioning, quality of life, and cognitive performance.

The study is conducted across two sites - The University of Hong Kong (Department of Psychology) and The Chinese University of Hong Kong (Department of Psychiatry). Findings are expected to clarify whether melatonin can augment the efficacy and sustainability of CBT-I in older adults, providing new insights into circadian-based strategies for improving sleep health in late life.

• Treatment Response of Insomnia [Time frame: Post-Treatment (one-week after treatment conclusion) for all participants, and at Post-Treatment 3-month and Post-Treatment 6-month for participants in the treatment groups.]
• Remission of insomnia [Time frame: Post-Treatment (one-week after treatment conclusion) for all participants, and at Post-Treatment 3-month and Post-Treatment 6-month for participants in the treatment groups.]
• Self Report Sleep Quality - The Pittsburgh Sleep Quality Index [Time frame: Baseline, Post-Treatment (one-week after treatment conclusion) for all participants, and at Post-Treatment 3-month and Post-Treatment 6-month for participants in the treatment groups.]
• Self-Report Chronotype Measures The Munich Chronotype Questionnaire [Time frame: Baseline, Post-Treatment (one-week after treatment conclusion) for all participants, and at Post-Treatment 3-month and Post-Treatment 6-month for participants in the treatment groups.]
• Self-Report Chronotype Preference: The Morningness-Eveningness Questionnaire [Time frame: Baseline, Post-Treatment (one-week after treatment conclusion) for all participants, and at Post-Treatment 3-month and Post-Treatment 6-month for participants in the treatment groups.]
• Self-report Mood Symptoms - Hospital Anxiety and Depression Scale [Time frame: Baseline, Post-Treatment (one-week after treatment conclusion) for all participants, and at Post-Treatment 3-month and Post-Treatment 6-month for participants in the treatment groups.]
• Self-report Daytime Sleepiness - Epworth Sleepiness Scale [Time frame: Baseline, Post-Treatment (one-week after treatment conclusion) for all participants, and at Post-Treatment 3-month and Post-Treatment 6-month for participants in the treatment groups.]
• Self-report Daytime Fatigue - Multidimensional Fatigue Inventory [Time frame: Baseline, Post-Treatment (one-week after treatment conclusion) for all participants, and at Post-Treatment 3-month and Post-Treatment 6-month for participants in the treatment groups.]
• Overall Severity of Clinical Symptoms [Time frame: Baseline, Post-Treatment (one-week after treatment conclusion) for all participants, and at Post-Treatment 3-month and Post-Treatment 6-month for participants in the treatment groups.]
• Overall Treatment Response [Time frame: Post-Treatment (one-week after treatment conclusion) for all participants, and at Post-Treatment 3-month and Post-Treatment 6-month for participants in the treatment groups.]
• Self Report Quality of Life - 36-Item Short Form Health Survey [Time frame: Baseline, Post-Treatment (one-week after treatment conclusion) for all participants, and at Post-Treatment 3-month and Post-Treatment 6-month for participants in the treatment groups.]
• Objective Cognitive Performance (attention/inhibitory ability) [Time frame: Baseline, Post-Treatment (one-week after treatment conclusion) for all participants, and at Post-Treatment 3-month and Post-Treatment 6-month for participants in the treatment groups.]