Mindfulness-based stress reduction interventions and cortisol regulation: A systematic review and meta-analysis.

BACKGROUND AND RATIONALE: Chronic stress is a growing public health concern, with cortisol widely recognized as its primary physiological biomarker. Mindfulness-based stress reduction (MBSR), a standardized multiweek program, has shown promise in improving psychological outcomes, yet its specific effects on cortisol levels have not been meta-analyzed. METHOD: We conducted a systematic review and meta-analysis of eligible MBSR trials, those that (a) reported pre- and postintervention cortisol levels and (b) controlled for timing of cortisol collection. RESULTS: Thirty-nine MBSR intervention studies met the inclusion criteria, with 2,059 participants. Within-group analyses revealed a statistically significant reduction in cortisol levels following MBSR (k = 53, g = -0.26, 95% confidence interval [-0.38, -0.14], particularly in randomized controlled trials (k = 26, g = -0.37 [-0.53, -0.20]), but not in uncontrolled studies (k = 18, g = -0.06 [-0.19, 0.07]). Between-group analyses showed MBSR to be significantly more effective than control conditions in lowering cortisol (k = 34, g = -0.38 [-0.56, -0.21). MBSR had larger reductions compared with inactive controls (k = 23, g = -0.42 [-0.63, -0.20]) and smaller reductions compared with active controls (k = 11, g = -0.29 [-0.54, -0.04]). Significant heterogeneity remained unexplained. CONCLUSIONS: MBSR interventions reduce cortisol, although results vary across studies. As MBSR provides a physiological benefit, it deserves greater implementation in stress reduction initiatives. (PsycInfo Database Record (c) 2026 APA, all rights reserved).