Contents lists available at ScienceDirect Journal of Psychosomatic Research journal homepage: www.elsevier.com/locate/jpsychores Review article Do workplace-based mindfulness meditation programs improve physiological indices of stress? A systematic review and meta-analysis Rachael A. Heckenberg a , Pennie Eddy a , Stephen Kent b , Bradley J. Wright b, ⁎ a School of Psychology and Public Health, La Trobe University, Wodonga, Victoria 3690, Australia b School of Psychology and Public Health, La Trobe University, Bundoora, Victoria 3086, Australia ARTICLE INFO Keywords: Mindfulness meditation MBSR Workplace stress HPA Cardiovascular Immunity ABSTRACT Objective: Mindfulness-based interventions (MBI) have been related with improved job satisfaction, wellbeing, health, and reduced workplace stress with employees. However, until now, synthesis of the evidence of the effect of MBIs on physiological indices associated with stress and ill-health has been lacking. Therefore the current systematic review aimed to synthesise the literature from employee samples to provide guidance for future investigations in terms of which physiological indicators and biological systems may be most impacted by MBIs. Methods: Electronic databases were searched. Studies that conducted a mindfulness-based program with an employee sample, which targeted workplace stress or work engagement, and measured a physiological outcome were selected for inclusion. Studies using either a between-group or within-group design were included. Nine papers were found to meet the inclusion criteria for our systematic review and meta-analysis of the literature. Results: MBIs were found to be effective in reducing cortisol production, as indicated by lowered high and low diurnal cortisol slopes. However, no changes were found for cortisol awakening response or concentrations for single a.m. and p.m. time-points. MBIs also improved autonomic balance, assessed by heart rate variability coherence measures, but not blood pressure. Sympathetic nervous system reactivity as measured by salivary alpha amylase was also reduced following MBI. While aspects of immune function were also improved following MBIs, specifically, increased antibody response to a viral vaccine and reduced C-reactive protein concentrations, each of these outcomes were only assessed in a single study. Conclusion: Taken together, the findings suggest that MBIs are a promising avenue for intervention for im- proving physiological indices of stress. Our findings suggest that changes in daytime cortisol secretion and HRV coherence may be particularly influenced by MBIs. Future studies should aim to assess multiple physiological indices to confirm the current findings and further improve current understanding of which biological systems (and indices within these systems) show responses indicative of reduced stress due to MBI. 1. Introduction Workplace stress is associated with costs to individuals, organiza- tions, and the community. It is consistently linked with poorer health outcomes, including cardiovascular disease [1,2], psychosomatic pro- blems, musculoskeletal disorders [3] and self-reported health [4,5]. Workplace stress is also associated with mental health issues, including depression and anxiety disorders [6,7]. Finally, it is also related to a number of pre-clinical markers of ill-health, including indicators of the immune system [8], cardiovascular health [9] and the hypothalamic- pituitary-adrenal (HPA) axis [10,11]. In addition to health concerns, the cost of workplace stress extends to the employer due to higher turnover rates [12,13], increased absences [14] and decreased work engagement [15]. Given the associated costs of workplace stress to individuals and society it is important to determine the most appro- priate interventions to reduce it. Interventions that are suitable to the workplace environment are rare [16], but a contemporary intervention with promising results across different populations and settings, including the workplace, is mindfulness meditation [17,18]. This is the act of purposefully paying attention to the present moment and being aware of mental states and processes with a sense of openheartedness, curiosity and kindness, and without judgement [19]. An increasing body of evidence demonstrates the effectiveness of mindfulness-based interventions (MBI) in improving job satisfaction, wellbeing, health, and reducing workplace stress [20–22]. However, a synthesis of the effects of MBIs on physiological indicators of workplace stress and ill-health is lacking. https://doi.org/10.1016/j.jpsychores.2018.09.010 Received 30 May 2018; Received in revised form 6 September 2018; Accepted 21 September 2018 ⁎ Corresponding author. E-mail address: b.wright@latrobe.edu.au (B.J. Wright). Journal of Psychosomatic Research 114 (2018) 62–71 0022-3999/ © 2018 Elsevier Inc. All rights reserved. T