Within-person longitudinal change in cardiac autonomic regulation during prolonged real-life psychosocial stress in healthy young adults: protocol for a systematic review

Full protocol (version 1.1, 3 November 2026) for a systematic review registered in PROSPERO as CRD420261558314 (https://www.crd.york.ac.uk/PROSPERO/view/CRD420261558314). The record was submitted on 1 November 2026 and published on 2 November 2026 after approval by all five authors; the version registered at that point was version 1.0 (31 October 2026). Version 1.1 follows an internal appraisal of the search strategy against the PRESS 2015 checklist: in Appendix A.1 the unqualified term displacement[tiab] was replaced by four qualified phrases, the sentence fragments "baseline and"[tiab] and "pre and post"[tiab] were deleted, and Appendix A.2 was rewritten from prose into a per-source table giving the controlled vocabulary, field syntax and proximity operator for each source. These changes were made before any search was executed and before any record was screened. The review examines within-person longitudinal change in cardiac autonomic regulation during prolonged real-life psychosocial stress in healthy young adults. This project archives the full protocol document and will hold subsequent protocol versions, search strategies, data-extraction forms and risk-of-bias templates. Companion review: cardiac autonomic regulation as a mediator between psycho-emotional state and physical working capacity, PROSPERO CRD420261556351, protocol archived at https://doi.org/10.17605/OSF.IO/GZMQ2. Related preregistration: prospective two-wave cohort study, https://doi.org/10.17605/OSF.IO/Z5M4S