This is a two-arm, with equal randomization (1:1 allocation ratio) parallel, superiority RCT. It compares a self-help smartphone-based CBT-I intervention to a waitlist control condition. The self-help treatment is delivered through “proACT-S”, a smartphone application developed by the corresponding author’s research team. Results from a pilot study showed that proACT-S was efficacious for treating insomnia and was positively received by the users . The current RCT is designed to test the efficacy of proACT-S in treating people with MDD and insomnia. Participants’ change in depressive and insomnia symptoms after the CBT-I intervention will be compared with the waitlist control group. The rationale for choosing waitlist control as the comparison condition is twofold: (1) it allows researchers to determine the effect of the intervention against not receiving treatment during the trial period; and (2) it ensures that all participants will eventually receive the treatment.
Prior to trial entry, participants complete a two-stage screening. Their eligibility is assessed by an online survey, followed by a telephone diagnostic interview. After the two-stage screening, the assessments, randomisation, and intervention are carried out via proACT-S. The research design is summarised in Figure 1. The full SPIRIT checklist is provided as Additional file 1.
This RCT is conducted in Hong Kong, where the 12-month prevalence of MDD among adults was estimated at 8.4% , and the weighted prevalence of insomnia among adults was 39.4% .
Inclusion criteria. To participate in this study, participants must fulfil the following inclusion criteria: (1) Hong Kong residents; (2) age ≥ 18 years; (3) sleep disturbance causes distress or impairment in social, occupational and other important areas of functioning for at least three nights per week for at least three months; (4) Insomnia Severity Index  score ≥ 8; (5) Patient Health Questionnaire (PHQ-9; ) score ≥ 10; (6) being able to read Chinese and type Chinese or English; (7) have a smartphone device (iOS or Android operating system) with Internet access; (8) have a regular email address; (9) willing to give informed consent and comply with the trial protocol; (10) difficulty initiating sleep, maintaining sleep, or early-morning awakening with inability to return to sleep at least once in the past two weeks; and (11) fulfilling International Statistical Classification of Diseases and Related Health Problems – Tenth Revision (ICD-10) diagnosis of depression (F32.00, F32.01, F32.10, F32.11, F32.2).
Exclusion criteria. Participants are excluded if they meet the following exclusion criteria: (1) Beck Depression Inventory-II (BDI-II) suicidal ideation score ≥ 2; or (2) receiving psychological treatment at least once per month; or (3) former proACT-S pilot clinical trial participants; or (4) currently taking prescribed psychiatric drugs such as antidepressants, tranquilizers, sleeping pills regularly; or (5) carrying a diagnosis of psychosis or schizophrenia; or (6) participating in any other academic studies or clinical trials related to insomnia and/or depression; or (7) having current suicidal plans or acts or have had suicidal plans or acts within the past 12 months.
Withdrawal criteria. Participants are withdrawn if, during the main study trial, they: (1) have concurrent psychological treatment at least once per month; or (2) are taking prescribed psychiatric drugs such as antidepressants, tranquilizers, sleeping pills regularly; or (3) are being diagnosed with psychosis or schizophrenia; or (4) are participating in any other academic studies or clinical trials related to insomnia and/or depression; or (5) have suicidal ideations defined as scoring ≥ 2 on the BDI-II suicidal ideation item; or (6) have experienced serious diseases, significant life events, hospitalization, or fatalities; or (7) withdraw their consent; or (8) 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. In addition, participants in the waitlist control group who fail the cross-condition contamination check are withdrawn. Participants in the waitlist control group are withdrawn if: (1) they have viewed part or all treatment module content as shown by people who are undergoing this study’s treatment or who have completed this study’s treatment, or who are very familiar with proACT-S (except the proACT-S project team); or (2) they have watched part or all of the treatment module videos included in proACT-S; or (3) they have completed part or all of the treatment module homework in proACT-S.
A two-stage screening is set up to ascertain whether or not participants fulfil the eligibility criteria. Stage 1 is an online rapid screening and is conducted in the Chinese language. Participants are screened for the aforementioned inclusion criteria 1 to 9, as well as for the aforementioned exclusion criteria 1 to 6. Demographic information is collected, including Hong Kong residency, age, predominant sleep complaints, and the extent of the resulting distress or impairment in social, occupational, and other important areas of functioning. Participants are asked if they are able to read Chinese and type Chinese or English, have a smartphone device (iOS or Android operating system) with Internet access, and have a regular email address. Participants’ severity of insomnia symptoms is measured by the Insomnia Severity Index, and each item is rated on a 4-point Likert scale, ranging from “not at all” to “extremely”. It has been validated in Hong Kong samples [33, 34] and has high internal consistency (Cronbach’s alpha = .81, ). Participants’ severity of depressive symptoms is measured by the PHQ-9, and each item is rated on a 4-point Likert scale, ranging from “not at all” to “nearly every day”. Participants’ suicidal ideation is assessed by BDI-II item 9. It has been validated in Hong Kong samples () and has high internal consistency (Cronbach’s alpha = .82, ). Participants are asked to indicate whether they are receiving any concurrent psychological treatment at least once per month, whether they had participated in the proACT-S pilot clinical trial, whether they are currently taking prescribed psychiatric medication, whether they are diagnosed psychosis or schizophrenia, and whether they are participating in any other academic studies or clinical trials related to insomnia and/or depression.
Stage 2 is a telephone diagnostic interview screening and is conducted in Cantonese. It is used to assess clinical depression and insomnia, which correspond to inclusion criteria 10 and 11. The clinical insomnia inclusion criterion is developed with reference to the Diagnostic and Statistical Manual of Mental Disorders – Fifth Edition (DSM-5, ) insomnia disorder diagnostic features. Difficulty initiating sleep is defined by a subjective sleep latency greater than 30 minutes, difficulty maintaining sleep is defined by frequent awakenings or problems returning to sleep within 30 minutes after awakenings, and early-morning awakening is defined by awakening at least 30 minutes before the scheduled time and the total sleep time before the awakening is less than 6.5 hours. The clinical depression inclusion criterion is based on the modified Chinese version of the Revised Clinical Interview Schedule (CIS-R, ) algorithm for ICD-10 Mild depressive episode without somatic symptoms (F32.00). The timeframe for items measuring ICD-10 depressive episode has changed from “in the past week” to “in the past two weeks” to tap the 2-week requirement for DSM-5 depressive episode diagnostic criteria. In order to meet the criteria of mild depressive episode without somatic symptoms, the participants need to fulfill the following four conditions: (1) having a minimum of two-week duration of depressive episode; (2) endorsing at least two prominent symptoms of depression – depressed mood, loss of interest, fatigue – in the past two weeks; (3) endorsing at least two of the other common depressive symptoms – reduced concentration, reduced self-esteem, ideas of guilt or worthlessness, pessimism about future, suicidal ideation, disturbed sleep, change in appetite with corresponding weight change – in the past two weeks; (4) obtaining a norm-based mental component score of ≤ 45 in the 12-item Short-Form Health Survey Version 1 (SF-12 Version 1) . Because no epidemiological research has been conducted to assess the screening utility of the SF-12 Version 1 mental health component scale for diagnosable depression in Hong Kong Chinese population, the cut-off score of ≤ 45 was chosen with reference to a study that assessed its diagnostic accuracy to predict depression in the general Australian population . In addition, Stage 2 screening is used to reject participants who meet the aforementioned exclusion criteria 2 to 7.
The self-help CBT-I treatment content is based on the Chinese translated version of a well-established CBT-I treatment manual entitled “Insomnia: A Clinician’s Guide to Assessment and Treatment” . CBT-I aims at changing dysfunctional cognitive beliefs and maladaptive behaviours that contribute to the maintenance of insomnia. The self-help CBT-I treatment is delivered in Chinese language in six consecutive weekly modules via proACT-S. The duration of each module is around 45 to 60 minutes. The content of each treatment module is displayed in Figure 3.
proACT-S has been pilot tested in a sample of 32 Hong Kong Chinese participants and, later, revamped to improve user experience. One current recommendation for engaging app users was to reduce the amount of text and, instead, to use videos to deliver treatment content . Therefore, animations were added to the text-based materials to enhance user experience. Following the literature recommendations [39, 40], more interactive components have been incorporated into the app. In particular, proACT-S now provides (a) a clear timeline to indicate the start date for each assessment and treatment module; (b) indicators for module and assessment completion; (c) more prompts for users to follow in completing the weekly homework; (d) a modifiable sleep diary that accommodates the sleep pattern of shift-workers; and (e) individualized homework feedback.
Reasons for discontinuation of CBT-I may include, but are not limited to, the following: (1) participants’ decision to discontinue treatment at any time for any reason; and (2) principal investigator’s decision to terminate treatment for the participants’ safety reasons at any time.
Depression severity. The 20-item Center for Epidemiologic Studies Depression Scale  is used to measure participants’ severity of depressive symptoms during the past week. Each item is rated on a 4-point Likert scale, ranging from “less than 1 day” to “5-7 days.” It has been validated in a Hong Kong sample and has high internal consistency (Cronbach’s alpha = .85, ).
Insomnia severity. The 7-item Insomnia Severity Index is used to assess participants’ severity of insomnia symptoms and the associated daytime impairment over the past two weeks. Each item is rated on a 4-point Likert scale, ranging from “not at all” to “extremely.” It has been validated in Hong Kong samples [33, 34] and has high internal consistency (Cronbach’s alpha = .81, )
Sleep quality. The 19-item Pittsburgh Sleep Quality Index  is used to measure participants’ sleep quality and disturbances during the past month. It has seven components, namely, sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, use of hypnotics, and daytime dysfunction. Each subscale is converted to a scale of 0 to 3. It has been validated in Hong Kong samples  and has good reliability (Cronbach’s alphas range from .59 to .63, ).
Subjective health. The SF-12 Version 1 is used to measure participants’ subjective physical and mental health status. The SF-12 Version 1 is scored using the recommended norm-based scoring with a mean of 50 and a standard deviation of 10 in the general U.S. population . It has been validated in Hong Kong samples [25, 46].
Anxiety. The 7-item Hospital Anxiety and Depression Scale – Anxiety subscale  is used to measure participants’ severity of anxiety symptoms during the past week. Each item is rated on a 4-point Likert scale. It has been validated in Hong Kong samples [25, 48] and has high reliability (Cronbach’s alpha = .8, ).
Treatment expectancy. The 6-item Credibility/Expectancy Questionnaire  has been modified to measure participants’ cognitively- and affectively-based expectancy towards the treatment. The original phrase “trauma symptoms” has been changed to “depressive symptoms” or “insomnia symptoms.” Four items are rated on a 9-point Likert scale, ranging from “not at all” to “very.” The remaining two items are rated on a 10-point Likert scale, ranging from “0%” to “100%.” It has been validated in cognitive behavioural therapeutic interventions for people with depression  or insomnia , and it has high internal consistency (Cronbach’s alphas range from .81 to .96).
Acceptability of treatment. The 26-item modified Participant Acceptability/Usability Rating Scale  is used to measure participants’ evaluation of the treatment via proACT-S on a 3-point Likert scale, ranging from “agree” to “disagree.” It has been validated in a pilot CBT-I study .
Demographics. Information about participants’ age, education level, marital status, occupation, and gender is obtained from the Stage 1 online rapid screening.
Clinical comorbidity. The number of participants with a current diagnosis of four major comorbidities (generalized anxiety disorder, phobias, obsessive-compulsive disorder, and panic disorder) can be estimated from the modified Chinese version of the CIS-R  administered in the Stage 2 telephone diagnostic interview screening. The modified Chinese version of the CIS-R  measures the ICD-10 diagnoses related to generalized anxiety disorder (F41.1), phobias (F40.00, F40.01, F40.1, F40.2), obsessive-compulsive disorder (F42), and panic disorder (F41.0).
Primary outcome assessments take place at baseline, post-intervention, and 6-week follow-up for both CBT-I and waitlist control conditions. The schedule of enrolment, interventions, and assessments is summarized in Table 1.
Individuals interested in participating are invited to complete a two-stage screening. In Stage 1 online rapid screening, they will complete an online survey to review their eligibility. Those who have passed the online rapid screening will receive a link within the Qualtrics platform to sign up for the Stage 2 telephone diagnostic interview screening. These telephone interviews are conducted by project assistants, who have been trained and supervised on the administration of the modified Chinese version of the CIS-R .
Individuals who do not meet the Stage 2 telephone diagnostic interview screening eligibility criteria will receive a list of references related to insomnia and depression produced by the Department of Health and the Social Welfare Department under the Government of the Hong Kong SAR. Information regarding crisis hotlines and integrated community centres for mental wellness are provided to those currently with suicidal plans or acts, or those who have had suicidal plans or acts within the past 12 months.
Individuals who have passed the two-stage screening are directed to download proACT-S either from App Store or Google Play. Eligible participants are guided to register for their own personal accounts to enter the main study trial. They then complete the baseline assessment via proACT-S. After that, they are randomly assigned in a 1:1 ratio either to CBT-I condition or waitlist control condition.
Participants in the CBT-I condition start the 6-week CBT-I immediately after randomization, complete the post-intervention assessment right after they finish the treatment, and complete the follow-up assessment six weeks after the post-intervention assessment. Participants in the waitlist control group wait for 6 weeks without the proACT-S intervention and then complete the post-intervention assessment six weeks after the baseline assessment. The waitlisted participants start CBT-I (equivalent to that of the CBT-I group) immediately after completing the post-intervention assessment, and they complete the follow-up assessment right after finishing the 6-week CBT-I.
Emails and WhatsApp reminders are sent to participants to increase their engagement and to enhance treatment compliance. Upon completion of the study, each eligible participant will receive cash coupons of HKD $100 as a token of appreciation for their participation. The proposed flow of participants is displayed in Figure 2.
The most updated meta-analysis of 28 self-help CBT-I RCTs  showed a significant treatment effect in alleviating depressive symptoms (Hedges’ g = 0.35) and insomnia symptoms (Hedges’ g = 0.79). It also found that the mean cumulative study attrition rates were 21.25% (SD = 15.31%) and 18.4% (SD = 18.21%) in the treatment and the waiting-list/routine care/no treatment/psychoeducation groups, respectively. Hence, a conservative small effect size (Cohen’s f = 0.2) and an attrition rate of 30% are estimated for the present study.
The sample size calculation for each of the three primary outcomes (i.e., insomnia severity, poor sleep quality, and depression severity) is based on mixed ANCOVA using GPower 3.1. To conduct a 2 (Condition: CBT-I versus waitlist control) × 2 (Assessment: Baseline versus post-intervention) mixed ANCOVA with an alpha value set at 0.05, two-sided, 80% power to detect a small effect of 0.2 (Cohen’s f) between two groups while controlling for 12 covariates (demographics, clinical comorbidity, treatment expectancy, and acceptability of treatment), a total sample size of 199 will be required. In order to account for 30% attrition, a total sample of 285 participants will be sufficient to detect a small effect size (Cohen’s f = 0.2) for the difference in the change in each of the three primary outcomes (i.e., insomnia severity, poor sleep quality, and depression severity) from baseline to post-intervention between CBT-I condition and waitlist control condition with a two-sided 5% significance level and a power of 80%.
Participants are recruited on a rolling basis through posters, web-based advertisements, departmental website, social media, and institutional mass mailing. A “proACT-S” Facebook page and a “proACT-S” Instagram account have also been set up for this project, where it contains the recruitment poster and local news articles related to insomnia and depression. Recruitment began in March 2019 and it is anticipated to be complete by the end of 2020.
One week following the completion of the baseline assessment, participants are randomly assigned in a ratio of 1:1 either to the CBT-I group or the waitlist control group using an online randomized algorithm (https://www.php.net/manual/en/function.random-int.php). The group assignment follows the simple randomization procedure and is completely automated to ensure allocation concealment.
The principal investigator is blind to both the outcome assessment and group assignment. The research team is blind to the outcome assessment because all three assessments are self-reported and carried out via the smartphone app, but is not blind to the group assignment as research members need to send emails and WhatsApp reminders to the participants to enhance treatment compliance. Efforts are made to minimize participants’ knowledge of treatment allocation by informing participants that the treatment start date is randomly assigned. Statistical analyses will be carried out by a researcher blind to the study protocol. In the unlikely event of a critical incident, the research team, as well as the principal investigator, will be authorized to break the blind and carefully record it on the Case Report Form.
Involvement of external parties
Psychiatric staff who were involved in validating the Chinese version of the CIS-R in Hong Kong were consulted regarding the telephone diagnostic interview training, item selection, and ICD-10 scoring algorithm. Clinical psychologists specialized in sleep disorders and potential end-users were invited by the research team to provide feedback regarding the study design (e.g., the measures, recruitment strategies, Facebook page), as well as proACT-S revamp and beta testing.
Adverse events, such as increased suicidal risk and hospital admission, study attrition rates, significant deterioration in primary outcomes, are monitored and recorded throughout the study trial. Treatment discontinuation decision may be made at the discretion of the principal investigator, for reasons concerning participants’ safety. The proportion of participants experiencing any adverse events in each group will be reported in the results of this RCT study.
Data analysis plan
The principle of intention-to-treat analysis will be adopted, in which all randomised participants with missing observations, from lost to follow-up or incomplete outcome assessments, will be handled by multiple imputation . Missing data is assumed to be 5%.
Chi-square tests and independent t-tests will be conducted to examine if participants in the CBT-I and waitlist control conditions differ in terms of demographic characteristics, clinical comorbidity, and baseline outcome scores. Multilevel linear mixed model based on the intention-to-treat principle will be used to calculate between-condition mean differences in the primary outcome changes in sleep quality, insomnia, and depression severity from baseline to post-intervention assessments. Multilevel linear mixed model based on the intention-to-treat principle will also be used to analyse secondary outcomes of the baseline to post-intervention change in subjective health and anxiety between CBT-I and waitlist control conditions. Clustering effect, significant baseline differences in demographics, clinical characteristics, and outcome variables will be adjusted for. Pair-sample t-tests based on the intention-to-treat principle will be used to analyse changes in primary outcomes, subjective health, and anxiety obtained at post-intervention and 6-week follow-up separately for each condition. All comparisons are planned with a 5% two-sided significance level. Bonferroni adjustment will be applied.
Ethics and dissemination
Consent is obtained electronically for the Stage 1 online rapid screening, verbally for the Stage 2 telephone diagnostic interview screening, and via the smartphone app proACT-S for the 6-week CBT-I intervention. The consent form explains that participation is voluntary; individuals could withdraw from the study at any time without any consequences.
Participants directly enter their data via Qualtrics during the Stage 1 online rapid screening and via proACT-S during the main trial study. Manual data entry from trained project assistants (i.e., telephone interviewers) is required for recording participants’ Stage 2 telephone diagnostic interview screening data. A Qualtrics survey based on the modified Chinese version of the CIS-R  was created to enable data entry, coding, and storage, in addition to standardizing the administration of Stage 2 screening across different trained telephone interviewers. Participants’ personal data are sent to the electronic server located at The University of Hong Kong, and protected using dual encryption. The principal investigator and the research team are given access to the dataset. Participants’ research files may be reviewed by the Human Research Ethics Committee of the University of Hong Kong in order to check that the study is being carried out correctly. Participants will not be identified by name in any report of the completed study. Their personal data will be kept for five years after the publication of the first original research paper, and research data without personal identifiers will be stored for long term retention at the Community Action Research Laboratory at The University of Hong Kong.
This protocol will be published in an open-access journal for public access. Researchers interested in using the de-identified dataset to test novel hypotheses could contact the corresponding author and submit a data proposal form to be reviewed by the research team. The study findings will be disseminated in peer-reviewed publications and conference presentations. Executive summaries will be made available on the proACT-S project website and disseminated to other organizations such as the funding agency and local news agencies.