This randomized controlled trial aims to examine the effectiveness of a self-help smartphone-delivered cognitive behavioral therapy for insomnia, compared to a waitlist control, in treating people with major depression and insomnia in Hong Kong.

Depression is a major public health concern. Emerging research has shown that cognitive behavioral therapy for insomnia (CBT-I) is effective in treating individuals with comorbid insomnia and depression. Traditional face-to-face CBT-I encounters many obstacles related to feasibility, accessibility, and help-seeking stigma. CBT-I delivered via smartphone application could be a potential solution. This two-arm parallel randomized controlled trial (RCT) aims to examine the effectiveness of a smartphone-based self-help CBT-I with a waitlist control group in treating people with major depression and insomnia in Hong Kong.

Participants complete an online rapid screening, followed by a telephone diagnostic interview. Those who meet the eligibility criteria are randomized in a ratio of 1:1 to receive either CBT-I immediately or to a waitlist control condition. The CBT-I consists of six weekly modules and is delivered through a smartphone application known as proACT-S. An online randomized algorithm is used to perform randomization to ensure allocation concealment. The primary outcomes are changes over the measurement points in sleep quality, insomnia severity and depression severity. The secondary outcomes include changes over the measurement points in anxiety, subjective health, treatment expectancy, and acceptability of treatment. Assessments are administered at baseline, post-intervention, and 6-week follow up. The recruitment is underway. Important adverse events, if any, are documented. Multilevel linear mixed model based on intention-to-treat principle will be conducted to examine the effectiveness of the CBT-I intervention

Participants in the CBT-I condition will start CBT-I immediately after randomization; while participants in the waitlist control group will start CBT-I (equivalent to that of the CBT-I group) immediately after completing the post-intervention assessment. It is hypothesized that, after the intervention, participants in the CBT-I condition will report a greater decrease in poor sleep quality, depression severity and insomnia severity than those in the waitlist control condition. It is also hypothesized that the reduction in poor sleep quality, depression severity and insomnia severity observed in the CBT-I condition will be maintained at 6-week follow-up. Furthermore, it is hypothesized that participants in the waitlist control condition will report a significant decrease in poor sleep quality, depression severity and insomnia severity after receiving CBT-I.

Stage 1 Screening (Online Survey) Inclusion Criteria:

• Hong Kong residents
• age ≥ 18 years
• predominant complaint of difficulty initiating or maintaining sleep or early morning awakening or non-restorative sleep with associated distress or impairment in social, occupational and other important areas of functioning for at least three nights per week for at least three months
• Insomnia Severity Index score ≥ 8
• Patient Health Questionnaire (PHQ-9) score ≥ 10
• being able to read Chinese and type Chinese or English
• have a smartphone device (iOS or Android operating system) with Internet access
• have a regular email address
• willing to give informed consent and comply with the trial protocol

Stage 1 Screening (Online Survey) Exclusion Criteria:

• Beck Depression Inventory II (BDI-II) suicidal ideation score ≥ 2
• receiving concurrent psychological treatment at least once per month
• former proACT-S pilot clinical trial participants
• currently taking prescribed psychiatric drugs such as antidepressants, tranquilizers, sleeping pills regularly
• carrying a diagnosis of psychosis or schizophrenia
• participating in any other academic studies or clinical trials related to insomnia and/or depression

Stage 2 Screening (Telephone Diagnostic Interview) Inclusion Criteria

• difficulty initiating sleep, maintaining sleep, or early-morning awakening with inability to return to sleep at least once in the past two weeks
• International Statistical Classification of Diseases and Related Health Problems - Tenth Revision diagnosis of depression (F32.00, F32.01, F32.10, F32.11, F32.2)

Stage 2 Screening (Telephone Diagnostic Interview) Exclusion Criteria

• having concurrent psychological treatment at least once per month
• currently taking prescribed psychiatric drugs such as antidepressants, tranquilizers, sleeping pills regularly
• carrying a diagnosis of psychosis or schizophrenia
• participating in any other academic studies or clinical trials related to insomnia and/or depression
• having current suicidal plans or acts or have had suicidal plans or acts within the past 12 months

Main Study Trial Withdrawal Criteria

• have concurrent psychological treatment at least once per month
• are taking prescribed psychiatric drugs such as antidepressants, tranquilizers, sleeping pills regularly
• are being diagnosed with psychosis or schizophrenia
• are participating in any other academic studies or clinical trials related to insomnia and/or depression
• have suicidal ideations defined as scoring ≥ 2 on the BDI-II suicidal ideation item
• have experienced serious diseases, significant life events, hospitalization, or fatalities
• withdraw their consent
• do not complete each assessment within two weeks, do not submit consent within two weeks after proACT-S personal account registration, or do not log into proACT-S within two weeks after random group assignment. (waitlist control group) fail the cross-condition contamination check