Can a sleep app ease chronic pain? new trial investigates

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: For a participant to be eligible, all inclusion criteria must be answered "yes": * Age ≥ 18 years. * Understand and write Danish. * Have smartphone access. * Pain for 3 months or longer. * Pain must be present on 'most days' or 'every day' within the past 3 months (will be checked by the question: 'In the past 3 months, how often did you have pain? - response options: 'never'; 'some days'; 'most days'; 'every day'). * Pain must limit life or work activities on 'some days', 'most days', or 'every day' within the past 3 months (will be checked by the question: 'In the past 3 months, how often did your pain limit your life or work activities - response options: never, some days, most days, every day * Average pain intensity equal to or higher than 4 on a 0-10 Numeric Rating Scale \[NRS\] in the past 7 days (ranging from 'no pain' to 'worst imaginable pain'). Insomnia symptoms (Insomnia Severity Index (ISI) score \> 10; moderate insomnia). Exclusion Criteria: For a participant to be eligible, all exclusion criteria must be answered "no": * Pregnancy or lactation (Pregnancy is screened for through self-reporting as no risks regarding pregnancy have been identified for the described study procedures). * Does not have daily assess to smartphone/tablet * Night shift during the time of the CBT-I treatment. * Currently receiving pharmacological treatment for insomnia (e.g. benzodiazepines, hypnotics etc.). * Severe psychiatric/somatic illnesses of relevance of their sleep (reported by participant). * Diagnosed sleep disorders (e.g., OSA, narcolepsy). * Does not have E-boks. * Known abuse of alcohol or other substances. * Suicide and self-harm thoughts (reported by participant). * People judged incapable, by the investigator, of understanding the participant instruction or who are not capable of carrying through the investigation. For the EEG subgroup only (60 patients): * Age ≥ 65 years * Anatomy of the outer ear making it impossible to do ear EEG monitoring. * Ear piercings that are not compatible with ear EEG. * Previous stroke or cerebral haemorrhage and any other structural cerebral disease. * Teeth grinding (bruxism). * Allergic contact dermatitis caused by metals or generally prone to skin irritation.