Acceptance and Commitment Therapy for Insomnia

Efficacy of Acceptance and Commitment Therapy as a Stand-Alone Treatment for Insomnia: Protocol of a Randomized Waitlist Controlled Trial

Insomnia is a common sleep problem that impacts both physical and mental health. Acceptance and Commitment Therapy for Insomnia (ACT-I) is proposed as a promising new treatment for insomnia. However, its effectiveness without overlapping behavioral components of the current standard treatment, cognitive behavioral therapy, remains largely unknown.

The main goal of this clinical trial is to test the efficacy of stand-alone ACT-I in adults with insomnia, compared to a waitlist control group. The second goal is to explore the potential working mechanisms of ACT-I, using network intervention analysis.

Adults with insomnia will be randomized to an ACT-I or waitlist group. Both the ACT-I treatment and waiting period span 7 weeks. Assessments take place at baseline (pre), after 4 weeks (mid), and after 8 weeks (post), followed by a 3- and 6-month follow-up for the ACT-I group.

The main questions this RCT aims to answer are:

• Is ACT-I superior to a waitlist control group in improving insomnia severity (primary outcome) in addition to sleep diary measures, anxiety, depression, general mental health, and sleep-related quality of life (secondary outcomes)?
• How do networks of insomnia symptoms or potential treatment processes (i.e., psychological (in)flexibility, sleep-related arousal, dysfunctional cognitions, and sleep-related safety behaviors) develop during and following ACT-I?

Study Overview

• Status: Completed
• Conditions: Insomnia
• Intervention / Treatment: Behavioral: Acceptance and Commitment Therapy for insomnia (ACT-I)

• Study Type: Interventional
• Enrollment (Actual): 93
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Netherlands
  • North Holland
    • Amsterdam, North Holland, Netherlands, 1018 WS
      • University of Amsterdam

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• insomnia severity index score ≥ 15
• clinical insomnia disorder diagnosis, as confirmed by the SCID-S-5 insomnia interview
• age of 18 years or above
• proficiency in Dutch
• ability to come on-site for the treatment sessions

Exclusion Criteria:

• previously received ACT
• started psychotherapy within the last 6 months or currently awaiting psychotherapy
• changed psychoactive medication in the last 3 months
• diagnosis of psychosis or schizophrenia
• severe depressive complaints (BDI-II score ≥ 29) or active suicidal ideation

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Acceptance and Commitment Therapy for insomnia (ACT-I); In this condition, participants receive five individual face-to-face 60-minute sessions of ACT-I psychotherapy within a 7-week treatment period.	Behavioral: Acceptance and Commitment Therapy for insomnia (ACT-I); During ACT-I patients are encouraged to let go of the struggle to control sleep and to focus on meaningful daytime activities. Treatment goals are addressed through ACT processes of creative hopelessness and self-as-context (session 1), acceptance (session 2), defusion (session 3), followed by values, committed action, and present moment awareness (sessions 4 and 5).; Other Names: ACT
No Intervention: Waitlist control; In this condition, participants fill out assessments only during a 7-week waiting period. After completing the post-assessment, participants in the control condition receive ACT-I treatment as well.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Insomnia severity	Insomnia severity is assessed with the Insomnia Severity Index (ISI). The ISI consists of seven items evaluating insomnia symptoms on a 5-point scale (range: 0-28). Higher scores indicate greater severity of insomnia symptoms.	Change from baseline to 8-weeks post-randomization

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Insomnia severity	Insomnia severity is assessed with the Insomnia Severity Index (ISI). The ISI consists of seven items evaluating insomnia symptoms on a 5-point scale (range: 0-28). Higher scores indicate greater severity of insomnia symptoms.	Change from baseline to 4-weeks post-randomization
Insomnia severity	Insomnia severity is assessed with the Insomnia Severity Index (ISI). The ISI consists of seven items evaluating insomnia symptoms on a 5-point scale (range: 0-28). Higher scores indicate greater severity of insomnia symptoms.	Change from baseline to 3-month follow-up (ACT-I group only)
Insomnia severity	Insomnia severity is assessed with the Insomnia Severity Index (ISI). The ISI consists of seven items evaluating insomnia symptoms on a 5-point scale (range: 0-28). Higher scores indicate greater severity of insomnia symptoms.	Change from baseline to 6-month follow-up (ACT-I group only)
General well-being	General well-being is assessed with the Mental Health Continuum Short Form (MHC-SF), which includes 14 items rated on a 6-point scale (range: 0-70). Higher scores indicate greater well-being.	Change from baseline to 4-weeks post-randomization
General well-being	General well-being is assessed with the Mental Health Continuum Short Form (MHC-SF), which includes 14 items rated on a 6-point scale (range: 0-70). Higher scores indicate greater well-being.	Change from baseline to 8-weeks post-randomization
General well-being	General well-being is assessed with the Mental Health Continuum Short Form (MHC-SF), which includes 14 items rated on a 6-point scale (range: 0-70). Higher scores indicate greater well-being.	Change from baseline to 3-month follow-up (ACT-I group only)
General well-being	General well-being is assessed with the Mental Health Continuum Short Form (MHC-SF), which includes 14 items rated on a 6-point scale (range: 0-70). Higher scores indicate greater well-being.	Change from baseline to 6-month follow-up (ACT-I group only)
Sleep-related quality of life	Sleep-related quality of life is evaluated using the Glasgow Sleep Impact Index (GSII). Respondents define and rate their three main domains of sleep-related impairment on a Visual Analog Scale (range: 0-100). Higher scores indicate more sleep-related impairment.	Change from baseline to 4-weeks post-randomization
Sleep-related quality of life	Sleep-related quality of life is evaluated using the Glasgow Sleep Impact Index (GSII). Respondents define and rate their three main domains of sleep-related impairment on a Visual Analog Scale (range: 0-100). Higher scores indicate more sleep-related impairment.	Change from baseline to 8-weeks post-randomization
Sleep-related quality of life	Sleep-related quality of life is evaluated using the Glasgow Sleep Impact Index (GSII). Respondents define and rate their three main domains of sleep-related impairment on a Visual Analog Scale (range: 0-100). Higher scores indicate more sleep-related impairment.	Change from baseline to 3-month follow-up (ACT-I group only)
Sleep-related quality of life	Sleep-related quality of life is evaluated using the Glasgow Sleep Impact Index (GSII). Respondents define and rate their three main domains of sleep-related impairment on a Visual Analog Scale (range: 0-100). Higher scores indicate more sleep-related impairment.	Change from baseline to 6-month follow-up (ACT-I group only)
Anxiety symptoms	Anxiety symptoms are assessed with the Hospital Anxiety and Depression Scale-Anxiety subscale (HADS-A), featuring seven items rated on a 4-point scale (range: 0-21). Higher scores indicate more anxiety symptoms.	Change from baseline to 4-weeks post-randomization
Anxiety symptoms	Anxiety symptoms are assessed with the Hospital Anxiety and Depression Scale-Anxiety subscale (HADS-A), featuring seven items rated on a 4-point scale (range: 0-21). Higher scores indicate more anxiety symptoms.	Change from baseline to 8-weeks post-randomization
Anxiety symptoms	Anxiety symptoms are assessed with the Hospital Anxiety and Depression Scale-Anxiety subscale (HADS-A), featuring seven items rated on a 4-point scale (range: 0-21). Higher scores indicate more anxiety symptoms.	Change from baseline to 3-month follow-up (ACT-I group only)
Anxiety symptoms	Anxiety symptoms are assessed with the Hospital Anxiety and Depression Scale-Anxiety subscale (HADS-A), featuring seven items rated on a 4-point scale (range: 0-21). Higher scores indicate more anxiety symptoms.	Change from baseline to 6-month follow-up (ACT-I group only)
Depression symptoms	Depression symptoms are assessed with the Patient Health Questionnaire depression scale (PHQ-9), a nine-item questionnaire scored on a 4-point scale (range: 0-36). Higher scores indicate more depression symptoms.	Change from baseline to 4-weeks post-randomization
Depression symptoms	Depression symptoms are assessed with the Patient Health Questionnaire depression scale (PHQ-9), a nine-item questionnaire scored on a 4-point scale (range: 0-36). Higher scores indicate more depression symptoms.	Change from baseline to 8-weeks post-randomization
Depression symptoms	Depression symptoms are assessed with the Patient Health Questionnaire depression scale (PHQ-9), a nine-item questionnaire scored on a 4-point scale (range: 0-36). Higher scores indicate more depression symptoms.	Change from baseline to 3-month follow-up (ACT-I group only)
Depression symptoms	Depression symptoms are assessed with the Patient Health Questionnaire depression scale (PHQ-9), a nine-item questionnaire scored on a 4-point scale (range: 0-36). Higher scores indicate more depression symptoms.	Change from baseline to 6-month follow-up (ACT-I group only)
Sleep diary: total sleep time	Total sleep time (in minutes) is assessed with the consensus sleep diary (CSD). Higher scores indicate higher total sleep time.	Change from baseline to 4-weeks post-randomization
Sleep diary: total sleep time	Total sleep time (in minutes) is assessed with the consensus sleep diary (CSD). Higher scores indicate higher total sleep time.	Change from baseline to 8-weeks post-randomization
Sleep diary: total sleep time	Total sleep time (in minutes) is assessed with the consensus sleep diary (CSD). Higher scores indicate higher total sleep time.	Change from baseline to 3-month follow-up (ACT-I group only)
Sleep diary: total sleep time	Total sleep time (in minutes) is assessed with the consensus sleep diary (CSD). Higher scores indicate higher total sleep time.	Change from baseline to 6-month follow-up (ACT-I group only)
Sleep diary: sleep onset latency	Sleep onset latency (in minutes) is assessed with the consensus sleep diary (CSD). Higher scores indicate longer sleep onset latency.	Change from baseline to 4-weeks post-randomization
Sleep diary: sleep onset latency	Sleep onset latency (in minutes) is assessed with the consensus sleep diary (CSD). Higher scores indicate longer sleep onset latency.	Change from baseline to 8-weeks post-randomization
Sleep diary: sleep onset latency	Sleep onset latency (in minutes) is assessed with the consensus sleep diary (CSD). Higher scores indicate longer sleep onset latency.	Change from baseline to 3-month follow-up (ACT-I group only)
Sleep diary: sleep onset latency	Sleep onset latency (in minutes) is assessed with the consensus sleep diary (CSD). Higher scores indicate longer sleep onset latency.	Change from baseline to 6-month follow-up (ACT-I group only)
Sleep diary: wake after sleep onset	Wake after sleep onset (in minutes) is assessed with the consensus sleep diary (CSD). Higher scores indicate longer wake time after sleep onset.	Change from baseline to 4-weeks post-randomization
Sleep diary: wake after sleep onset	Wake after sleep onset (in minutes) is assessed with the consensus sleep diary (CSD). Higher scores indicate longer wake time after sleep onset.	Change from baseline to 8-weeks post-randomization
Sleep diary: wake after sleep onset	Wake after sleep onset (in minutes) is assessed with the consensus sleep diary (CSD). Higher scores indicate longer wake time after sleep onset.	Change from baseline to 3-month follow-up (ACT-I group only)
Sleep diary: wake after sleep onset	Wake after sleep onset (in minutes) is assessed with the consensus sleep diary (CSD). Higher scores indicate longer wake time after sleep onset.	Change from baseline to 6-month follow-up (ACT-I group only)
Sleep diary: sleep efficiency	Sleep efficiency (in percentage) is assessed with the consensus sleep diary (CSD), calculated as the total sleep time*100 divided by the time in bed. Higher scores indicate higher sleep efficiency.	Change from baseline to 4-weeks post-randomization
Sleep diary: sleep efficiency	Sleep efficiency (in percentage) is assessed with the consensus sleep diary (CSD), calculated as the total sleep time*100 divided by the time in bed. Higher scores indicate higher sleep efficiency.	Change from baseline to 8-weeks post-randomization
Sleep diary: sleep efficiency	Sleep efficiency (in percentage) is assessed with the consensus sleep diary (CSD), calculated as the total sleep time*100 divided by the time in bed. Higher scores indicate higher sleep efficiency.	Change from baseline to 3-month follow-up (ACT-I group only)
Sleep diary: sleep efficiency	Sleep efficiency (in percentage) is assessed with the consensus sleep diary (CSD), calculated as the total sleep time*100 divided by the time in bed. Higher scores indicate higher sleep efficiency.	Change from baseline to 6-month follow-up (ACT-I group only)
Psychological flexibility	Psychological flexibility is assessed with the Multidimensional Psychological Flexibility Inventory short form (MPFI-24). The subscale psychological flexibility consists of 12 items, scored on a 6-point scale (range: 12-72). Higher scores indicate greater psychological flexibility.	Change from baseline to 4-weeks post-randomization
Psychological flexibility	Psychological flexibility is assessed with the Multidimensional Psychological Flexibility Inventory short form (MPFI-24). The subscale psychological flexibility consists of 12 items, scored on a 6-point scale (range: 12-72). Higher scores indicate greater psychological flexibility.	Change from baseline to 8-weeks post-randomization
Psychological flexibility	Psychological flexibility is assessed with the Multidimensional Psychological Flexibility Inventory short form (MPFI-24). The subscale psychological flexibility consists of 12 items, scored on a 6-point scale (range: 12-72). Higher scores indicate greater psychological flexibility.	Change from baseline to 3-month follow-up (ACT-I group only)
Psychological flexibility	Psychological flexibility is assessed with the Multidimensional Psychological Flexibility Inventory short form (MPFI-24). The subscale psychological flexibility consists of 12 items, scored on a 6-point scale (range: 12-72). Higher scores indicate greater psychological flexibility.	Change from baseline to 6-month follow-up (ACT-I group only)
Psychological inflexibility	Psychological inflexibility is assessed with the Multidimensional Psychological Flexibility Inventory short form (MPFI-24). The subscale psychological inflexibility consists of 12 items, scored on a 6-point scale (range: 12-72). Higher scores indicate greater psychological inflexibility.	Change from baseline to 4-weeks post-randomization
Psychological inflexibility	Psychological inflexibility is assessed with the Multidimensional Psychological Flexibility Inventory short form (MPFI-24). The subscale psychological inflexibility consists of 12 items, scored on a 6-point scale (range: 12-72). Higher scores indicate greater psychological inflexibility.	Change from baseline to 8-weeks post-randomization
Psychological inflexibility	Psychological inflexibility is assessed with the Multidimensional Psychological Flexibility Inventory short form (MPFI-24). The subscale psychological inflexibility consists of 12 items, scored on a 6-point scale (range: 12-72). Higher scores indicate greater psychological inflexibility.	Change from baseline to 3-month follow-up (ACT-I group only)
Psychological inflexibility	Psychological inflexibility is assessed with the Multidimensional Psychological Flexibility Inventory short form (MPFI-24). The subscale psychological inflexibility consists of 12 items, scored on a 6-point scale (range: 12-72). Higher scores indicate greater psychological inflexibility.	Change from baseline to 6-month follow-up (ACT-I group only)
Sleep-related arousal	Sleep-related arousal will be assessed with the Pre-Sleep Arousal Scale (PSAS), which comprises 16 items scored on a 5-point scale (range: 16-80). Higher scores indicate higher sleep-related arousal.	Change from baseline to 4-weeks post-randomization
Sleep-related arousal	Sleep-related arousal will be assessed with the Pre-Sleep Arousal Scale (PSAS), which comprises 16 items scored on a 5-point scale (range: 16-80). Higher scores indicate higher sleep-related arousal.	Change from baseline to 8-weeks post-randomization
Sleep-related arousal	Sleep-related arousal will be assessed with the Pre-Sleep Arousal Scale (PSAS), which comprises 16 items scored on a 5-point scale (range: 16-80). Higher scores indicate higher sleep-related arousal.	Change from baseline to 3-month follow-up (ACT-I group only)
Sleep-related arousal	Sleep-related arousal will be assessed with the Pre-Sleep Arousal Scale (PSAS), which comprises 16 items scored on a 5-point scale (range: 16-80). Higher scores indicate higher sleep-related arousal.	Change from baseline to 6-month follow-up (ACT-I group only)
Dysfunctional sleep-related cognitions	Dysfunctional sleep-related cognitions will be evaluated by the short form of the Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS-16), which includes 16 items scored on an 11-point agreement scale (range: 0-160). Higher scores indicate more dysfunctional sleep-related cognitions.	Change from baseline to 4-weeks post-randomization
Dysfunctional sleep-related cognitions	Dysfunctional sleep-related cognitions will be evaluated by the short form of the Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS-16), which includes 16 items scored on an 11-point agreement scale (range: 0-160). Higher scores indicate more dysfunctional sleep-related cognitions.	Change from baseline to 8-weeks post-randomization
Dysfunctional sleep-related cognitions	Dysfunctional sleep-related cognitions will be evaluated by the short form of the Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS-16), which includes 16 items scored on an 11-point agreement scale (range: 0-160). Higher scores indicate more dysfunctional sleep-related cognitions.	Change from baseline to 3-month follow-up (ACT-I group only)
Dysfunctional sleep-related cognitions	Dysfunctional sleep-related cognitions will be evaluated by the short form of the Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS-16), which includes 16 items scored on an 11-point agreement scale (range: 0-160). Higher scores indicate more dysfunctional sleep-related cognitions.	Change from baseline to 6-month follow-up (ACT-I group only)
Sleep-related safety behaviors	Sleep-related safety behaviors will be measured with the sleep-related behaviors questionnaire short form (SRBQ-20), which consists of 20 items on coping with fatigue or improving sleep, scored on a 5-point scale (range: 0-80), with higher scores indicating more sleep-related safety behavior.	Change from baseline to 4-weeks post-randomization
Sleep-related safety behaviors	Sleep-related safety behaviors will be measured with the sleep-related behaviors questionnaire short form (SRBQ-20), which consists of 20 items on coping with fatigue or improving sleep, scored on a 5-point scale (range: 0-80), with higher scores indicating more sleep-related safety behavior.	Change from baseline to 8-weeks post-randomization
Sleep-related safety behaviors	Sleep-related safety behaviors will be measured with the sleep-related behaviors questionnaire short form (SRBQ-20), which consists of 20 items on coping with fatigue or improving sleep, scored on a 5-point scale (range: 0-80), with higher scores indicating more sleep-related safety behavior.	Change from baseline to 3-month follow-up (ACT-I group only)
Sleep-related safety behaviors	Sleep-related safety behaviors will be measured with the sleep-related behaviors questionnaire short form (SRBQ-20), which consists of 20 items on coping with fatigue or improving sleep, scored on a 5-point scale (range: 0-80), with higher scores indicating more sleep-related safety behavior.	Change from baseline to 6-month follow-up (ACT-I group only)

Collaborators and Investigators

• Sponsor: University of Amsterdam
• Investigators: Principal Investigator: Looman I Mathilde, MSc, University of Amsterdam

Publications and helpful links

Helpful Links

• Analysis plan for network intervention analysis (NIA), registered on OSF on the 13th of April.

Study record dates

Study Major Dates

• Study Start (Actual): April 2, 2024
• Primary Completion (Actual): January 13, 2026
• Study Completion (Actual): January 13, 2026

Study Registration Dates

• First Submitted: March 21, 2024
• First Submitted That Met QC Criteria: March 21, 2024
• First Posted (Actual): March 28, 2024

Study Record Updates

• Last Update Posted (Actual): April 17, 2026
• Last Update Submitted That Met QC Criteria: April 13, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Acceptance and Commitment Therapy; randomized controlled trial; efficacy; mechanisms; ACT-I; stand-alone
• Additional Relevant MeSH Terms: Nervous System Diseases; Mental Disorders; Sleep Wake Disorders; Sleep Disorders, Intrinsic; Dyssomnias; Sleep Initiation and Maintenance Disorders
• Other Study ID Numbers: UniversityAmsterdam

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Data will be made available upon requests.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No