InsomniaNCT06336551
Acceptance and Commitment Therapy for Insomnia
A study testing Acceptance and Commitment Therapy for insomnia (ACT-I) in people with Insomnia, run by University of Amsterdam at 1 site in Netherlands.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Insomnia
- What is being tested?
- Acceptance and Commitment Therapy for insomnia (ACT-I)
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 93 participants
- Where
- 1 siteNetherlands
- Study dates
- 2 Apr 2024to 13 Jan 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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
Who cannot join
- 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
Trial locations and contacts
1 site in 1 country.
Netherlands1 site
University of Amsterdam
Amsterdam, North Holland, 1018 WS
About this study
Official title: 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.
Read more
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?
- Conditions
- Insomnia
- Being tested
- Acceptance and Commitment Therapy for insomnia (ACT-I)
- Keywords
- Acceptance and Commitment Therapy, ACT-I, stand-alone, efficacy, mechanisms, randomized controlled trial
- Medical subject headings
- Sleep Initiation and Maintenance Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Acceptance and Commitment Therapy for insomnia (ACT-I)Behavioural
Also called ACT
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).
| Study group | Role | What they receive |
|---|---|---|
| Acceptance and Commitment Therapy for insomnia (ACT-I) | Experimental | In this condition, participants receive five individual face-to-face 60-minute sessions of ACT-I psychotherapy within a 7-week treatment period. Receives: Behavioral: Acceptance and Commitment Therapy for insomnia (ACT-I) |
| Waitlist control | No intervention | 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 being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: Change from baseline to 8-weeks post-randomization
Secondary outcomes (55)
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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: Change from baseline to 6-month follow-up (ACT-I group only)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted28 Mar 2024
- Study start2 Apr 2024
- Primary completion13 Jan 2026
- Study completion13 Jan 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for InsomniaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 93 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Amsterdam
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Mathilde Looman, University of Amsterdam
- Investigators
- Looman I Mathilde, MSc, Principal investigator, University of Amsterdam
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06336551
- Sponsor's protocol ID
- UniversityAmsterdam
- Status last verified
- Apr 2026
- First submitted
- 21 Mar 2024
- Last updated
- 17 Apr 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Data will be made available upon requests.
Study at a glance
From the registry record, last updated by the sponsor on 17 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Efficacy of Acceptance and Commitment Therapy as a Stand-Alone Treatment for Insomnia: Protocol of a Randomized Waitlist Controlled Trial
- ClinicalTrials.gov ID
- NCT06336551
- Acronym / sponsor ID
- UniversityAmsterdam
- Conditions
- Insomnia
- Keywords
- Acceptance and Commitment Therapy, ACT-I, stand-alone, efficacy, mechanisms, randomized controlled trial
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 93 participants (actual)
- Lead sponsor
- University of AmsterdamUniversity, hospital or other
- Study start
- 2 Apr 2024 (actual)
- Primary completion
- 13 Jan 2026 (actual)
- Study completion
- 13 Jan 2026 (actual)
- First posted
- 28 Mar 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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 design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Acceptance and Commitment Therapy for insomnia (ACT-I) | Experimental | Behavioral: 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. |
| Waitlist control | No intervention | –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. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- 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
Key exclusion criteria (5 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Acceptance and Commitment Therapy for insomnia (ACT-I)Also: ACTDuring 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). | Behavioural | Acceptance and Commitment Therapy for insomnia (ACT-I) |
Primary outcome
Insomnia severity
Time frame: Change from baseline to 8-weeks post-randomization
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.
55 secondary outcomes
Insomnia severity
Time frame: Change from baseline to 4-weeks post-randomization
Insomnia severity
Time frame: Change from baseline to 3-month follow-up (ACT-I group only)
Insomnia severity
Time frame: Change from baseline to 6-month follow-up (ACT-I group only)
General well-being
Time frame: Change from baseline to 4-weeks post-randomization
General well-being
Time frame: Change from baseline to 8-weeks post-randomization
General well-being
Time frame: Change from baseline to 3-month follow-up (ACT-I group only)
General well-being
Time frame: Change from baseline to 6-month follow-up (ACT-I group only)
Sleep-related quality of life
Time frame: Change from baseline to 4-weeks post-randomization
Sleep-related quality of life
Time frame: Change from baseline to 8-weeks post-randomization
Sleep-related quality of life
Time frame: Change from baseline to 3-month follow-up (ACT-I group only)
Sleep-related quality of life
Time frame: Change from baseline to 6-month follow-up (ACT-I group only)
Anxiety symptoms
Time frame: Change from baseline to 4-weeks post-randomization
Anxiety symptoms
Time frame: Change from baseline to 8-weeks post-randomization
Anxiety symptoms
Time frame: Change from baseline to 3-month follow-up (ACT-I group only)
Anxiety symptoms
Time frame: Change from baseline to 6-month follow-up (ACT-I group only)
Depression symptoms
Time frame: Change from baseline to 4-weeks post-randomization
Depression symptoms
Time frame: Change from baseline to 8-weeks post-randomization
Depression symptoms
Time frame: Change from baseline to 3-month follow-up (ACT-I group only)
Depression symptoms
Time frame: Change from baseline to 6-month follow-up (ACT-I group only)
Sleep diary: total sleep time
Time frame: Change from baseline to 4-weeks post-randomization
Sleep diary: total sleep time
Time frame: Change from baseline to 8-weeks post-randomization
Sleep diary: total sleep time
Time frame: Change from baseline to 3-month follow-up (ACT-I group only)
Sleep diary: total sleep time
Time frame: Change from baseline to 6-month follow-up (ACT-I group only)
Sleep diary: sleep onset latency
Time frame: Change from baseline to 4-weeks post-randomization
Sleep diary: sleep onset latency
Time frame: Change from baseline to 8-weeks post-randomization
Sleep diary: sleep onset latency
Time frame: Change from baseline to 3-month follow-up (ACT-I group only)
Sleep diary: sleep onset latency
Time frame: Change from baseline to 6-month follow-up (ACT-I group only)
Sleep diary: wake after sleep onset
Time frame: Change from baseline to 4-weeks post-randomization
Sleep diary: wake after sleep onset
Time frame: Change from baseline to 8-weeks post-randomization
Sleep diary: wake after sleep onset
Time frame: Change from baseline to 3-month follow-up (ACT-I group only)
Sleep diary: wake after sleep onset
Time frame: Change from baseline to 6-month follow-up (ACT-I group only)
Sleep diary: sleep efficiency
Time frame: Change from baseline to 4-weeks post-randomization
Sleep diary: sleep efficiency
Time frame: Change from baseline to 8-weeks post-randomization
Sleep diary: sleep efficiency
Time frame: Change from baseline to 3-month follow-up (ACT-I group only)
Sleep diary: sleep efficiency
Time frame: Change from baseline to 6-month follow-up (ACT-I group only)
Psychological flexibility
Time frame: Change from baseline to 4-weeks post-randomization
Psychological flexibility
Time frame: Change from baseline to 8-weeks post-randomization
Psychological flexibility
Time frame: Change from baseline to 3-month follow-up (ACT-I group only)
Psychological flexibility
Time frame: Change from baseline to 6-month follow-up (ACT-I group only)
Psychological inflexibility
Time frame: Change from baseline to 4-weeks post-randomization
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 17 Apr 2026.
- Analysis plan for network intervention analysis (NIA), registered on OSF on the 13th of April.Link provided by the sponsor.
- Individual participant dataSharing planned: No. Data will be made available upon requests.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Looman I Mathilde, MSc principal investigator
University of Amsterdam
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Acceptance and Commitment Therapy for insomnia (ACT-I) in people with Insomnia, run by University of Amsterdam at 1 site in Netherlands.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 17 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Netherlands. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Insomnia severity (time frame: Change from baseline to 8-weeks post-randomization). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 17 Apr 2026.