STUDY PROTOCOL Open Access © The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. ter Avest et al. BMC Psychology (2023) 11:183 https://doi.org/10.1186/s40359-023-01127-0 BMC Psychology † Milou M ter Avest and Annelieke S M van Velthoven shared first authors. *Correspondence: Milou M ter Avest milou.teravest@radboudumc.nl Full list of author information is available at the end of the article Abstract Background Many patients with Inflammatory Bowel Diseases (IBD) suffer from psychological distress, fatigue and sleep disturbances, which are associated with reduced quality of life (QoL) and increased societal costs. Only limited psychosocial treatment options are available. As Mindfulness-Based Cognitive Therapy (MBCT) has demonstrated to improve psychological distress, QoL and sleep in other populations, MBCT might also be effective in patients with IBD. Methods The MindIBD study is a prospective, multicentre, randomised controlled trial comparing MBCT plus Treatment As Usual (TAU) versus TAU alone in a targeted number of 136 IBD patients in remission, aged 16 years and older with at least mild psychological distress (Hospital Anxiety and Depression Scale (HADS) total score ≥ 11). Primary outcome is reduction of psychological distress post-intervention, measured by the HADS. In addition, the effect of MBCT on sleep quality (including actigraphy and electroencephalography recordings), fatigue, disease activity, perceived disease control, QoL and positive mental health will be examined. Assessments will be conducted at baseline and at 3, 6, 9 and 12 months follow-up. Cost-effectiveness will be determined and a process evaluation will be conducted. Discussion This study will provide valuable insight into the clinical effect of MBCT on psychological distress, sleep quality, fatigue and QoL in IBD patients and into the cost-effectiveness. If effective, MBCT can be a valuable addition Effectiveness of Mindfulness-Based Cognitive Therapy in reducing psychological distress and improving sleep in patients with Inflammatory Bowel Disease: study protocol for a multicentre randomised controlled trial (MindIBD). Milou M ter Avest 1,2,3*† , Annelieke S M van Velthoven 1,2† , Anne E M Speckens 1,2 , Gerard Dijkstra 4 , Martin Dresler 2 , Carmen S Horjus 5 , Tessa E H Römkens 3 , Ellen M Witteman 6 , Willemijn A van Dop 7 , Quirine M Bredero 8 , Loes H C Nissen 3 and Marloes J Huijbers 1,2