The primary aim of this study is to investigate the effect of Internet-delivered Acceptance and commitment therapy for emotional distress and comorbid chronic pain. A pilot study ( N=5-10) will be conducted to test the intervention and assessment procedures. The participants will go through an active internet-based ACT treatment focused on education about emotional distress and pain, as well as behavior change through exercises targeting the processes mindfulness, cognitive defusion and acceptance. The treatment is delivered on a safe internet platform. Participants have planned telephone contact with their assigned psychologist 2 times during the program and can also contact their psychologist via a message system in the platform and expect answer within 48 hours.

Objective The primary aim of this study is to investigate the effect of Internet-delivered Acceptance and commitment therapy (iACT)for emotional distress and chonirc pain.

Sample size 5-10 participants.

Trial design All participants are offered treatment. Participants are recruited from the Pain Rehabilitation Unit at Skåne University Hospital. The unit is a government supported, regional specialist center focused on assessment and treatment of chronic pain and related disability.

Assessments Baseline and posttreatment (2 weeks after treatment) assessments will be conducted. Self-report measures will also be collected at baseline, post-treatment as well as during a 3-month follow up.

Assessment includes:Pre-and post assessment Assessors collected demographic information and self-report measures. During the pre-assessment the Mini International Neuropsychiatric Interview 5.0 (MINI) was administered to detect the presence of other comorbid disorders and assess inclusion criteria and rule out exclusion criteria.

During treatment During treatment the treatment credibility scale will be administered to assess the patients' perceptions of how credible the treatment was following the introduction of the treatment rationale and the main treatment components (included in the internet program).

Safety parameters: Participants can report any adverse events during treatment, at posttreatment and follow-up assessment. Partcipants will be monitored daily (see below).

Post-treatment exit interview At the post-assessment, the assigned assessor asked participants about their satisfaction with and experience of the program, what they found helpful or unhelpful and suggestions for future improvements.

Measures will be taken at baseline, 2-weeks, 3 months follow-up. Self-report measures will be mailed to participants

We also intend to conduct a single-case design with daily data collection during a baseline phase (A) and an intervention phase (B). The treatment intervention spans 8 weeks.

For the daily data collection, we will again use a shortened set of measures comprising approximately 10 items focusing on psychological flexibility, pain intensity, and pain interference. Data will be collected via a digital platform, with secure handling of any personal data.

Main statistical analysis Between-group estimates on outcome will be conducted using repeated measurements. The analyses will be conducted using intention to treat principles and post hoc comparisons. We will also conduct randomization test for the A/B single case data collection.

Inclusion Criteria:

emotional distress characterized by clinically significant symptoms of anxiety or depression age between 18-65 years were fully examined medically and had received medical treatment if indicated were able to be an active part of the rehabilitation process, regain functioning in different life areas and participate in treatment interventions for approximately 5 hours every week stable dose of medication able to read and write in Swedish had access to a smart phone or computer with internet access

Exclusion Criteria:

had acute or severe psychiatric disorders or symptoms that warranted designation as the primary disorder (ongoing substance dependence, untreated bipolar disorder, OCD, psychotic symptoms, severe depression, PTSD) were actively abusing analgesic medications (including narcotics), alcohol or other drugs had great difficulty to harbour and handle strong emotions that could lead to emotional outbursts or self-harming behavior had health risks due to medical reasons; had social or economic difficulties or lack of social support that hindered behavior change current severe suicidal ideation that warranted immediate intervention (indicated by the MINI)