Procedure
ABI
This randomized controlled trial was conducted between September 2018 and February 2022, with the first patient included on 10 September 2018. Potential participants were referred by their neuropsychologists in the first weeks of their rehabilitation program. Neuropsychologists screened possible participants for inclusion and exclusion criteria and gave information about the study. All ABI patients who met the inclusion criteria were able to receive the add-on sleep therapy, regardless of their participation in the study. When participants were interested in participation in the study, the researcher (LP) was informed. A final check on inclusion- and exclusion criteria was performed by the researcher. After obtaining the signed informed consents, participants were randomly allocated to either the CBT-I + TAU or TAU only group using a computer-generated randomization program (Research Randomizer; The CBT-I + TAU group started with the six-week sleep intervention, in addition to their rehabilitation treatment as usual. Patients in the TAU only group were placed on a wait-list for six weeks, while receiving rehabilitation treatment as usual (based on indication, which consisted of physiotherapy, occupational therapy, neuropsychological treatment, speech therapy). Demographic and injury-related information was obtained and the self-report measures (PSQI, HADS, DMFS, DBAS-16) were filled in (T0 for the treatment group) during the first session. Note that results of the baseline measures were not discussed with the participants during the first session. At the end of the sleep intervention, pre-and post- assessments were discussed with patients during the last session.A follow-up measurement took place in the CBT-I + TAU group to examine whether the effects of the add-on sleep intervention were maintained. The CBT-I + TAU group completed the follow-up assessment 3 months after completing the intervention. Note that the follow-up assessment was limited to the CBT-I + TAU group, as the TAU only group also received the intervention following the 6-week waiting period.Assessments for the CBT-I + TAU group were built in the treatment sessions, with T0 in the first session and T6 after six weeks in the fourth session and administered by the therapists. At the start of the waiting period, a baseline assessment (T0) was administered by one of the researchers. T6 was carried out in the first session of the intervention. Patients and therapists were aware of the group allocation as the CBT-I + TAU group received the therapy in addition to their rehabilitation treatment as usual, while the TAU only group received the intervention after six weeks. The researcher was not blinded, since her role was to communicate with the planning staff to ensure patients started the intervention at the appropriate timepoint. A CONSORT flow diagram showing the content of the interventions is presented in 