Supplementary file 1_Exercise interventions for sleep and cognitive dysfunction in shift workers: a systematic review of randomized trials.docx

Background and objectivesShift work disrupts circadian rhythms and contributes to poor sleep, cardiometabolic risk, and cognitive impairment, which is especially concerning in safety-critical professions. While exercise improves sleep and cognition in the general population, its effects in shift-working adults remain unclear. This review synthesizes randomized controlled trials (RCT) evidence on structured exercise training to determine its impact on sleep and cognitive outcomes in shift workers, and examines intervention characteristics, mechanistic pathways, and barriers to clinical translation.
Materials and methodsFollowing PRISMA and Cochrane recommendations, six databases were searched from inception to January 2025 for RCTs involving adult shift workers and structured exercise (aerobic, resistance, combined, HIIT, or in-shift activity breaks). Primary outcomes were sleep quality, quantity, and continuity assessed using the Pittsburgh Sleep Quality Index (PSQI), actigraphy or polysomnography, and the Karolinska Sleepiness Scale (KSS), as well as cognitive performance and alertness measured by the Psychomotor Vigilance Task (PVT). Risk of bias (RoB 2.0) and methodological quality (PEDro) were assessed. Due to heterogeneity in interventions and outcome measures, results were narratively synthesized.
ResultsTen RCTs (n = 420; 60% healthcare settings) predominantly evaluated aerobic or mixed modalities. Eight studies reported significant improvements in PSQI, total sleep time, sleep efficiency, or wake after sleep onset, although effect sizes and clinical relevance were inconsistent. Three RCTs demonstrated improvements in alertness, reaction time, and short-term memory, particularly when interventions were timed post-shift or delivered as supervised workplace sessions. Mechanistic evidence from six studies indicated circadian phase shifting, improved autonomic balance assessed by heart rate variability (HRV), and reduced inflammatory markers. However, 80% had “some concerns” or “high” risk of bias, and adherence barriers such as fatigue and irregular schedules were common.
ConclusionStructured exercise programs, tailored to shift pattern and individual chronotype, show promise for enhancing sleep and cognitive function in shift workers. Workplace-based, supervised interventions maximize adherence and real-world applicability. Future adequately powered RCTs with standardized outcomes, mechanistic markers, and sector-diverse samples are needed before guideline-level recommendations can be established.
Systematic review registrationIdentifier, PROSPERO CRD420250650538. https://www.crd.york.ac.uk/PROSPERO/view/CRD420250650538.