Investigating the Specific Effects of an Online Mindfulness-Based Self-Help Intervention on Stress and Underlying Mechanisms.

Previous research examining the effects of mindfulness-based interventions (MBIs) and their mechanisms of change has been hampered by failure to control for non-specific factors, such as social support and interaction with group members, facilitator contact and expectation of benefit, meaning that it remained possible that benefits of MBIs could have been attributable, perhaps entirely, to non-specific elements. This experimental study examined the effects of a 2-week online mindfulness-based self-help (MBSH) intervention compared to a well-matched classical music control condition and a waitlist control condition on perceived stress. This study also tested mindfulness, self-compassion and worry as mechanisms of the effects of MBSH versus both control conditions on stress. University students and staff (N = 214) were randomised to MBSH, classical music, or waitlist conditions and completed self-report measures pre-, mid- and post-intervention. Post-intervention, MBSH was found to significantly reduce stress compared to both control conditions. Bootstrapping-based mediation analyses used standardised residualised change scores for all variables, with mediators computed as change from baseline to mid-intervention, and the outcome computed as change from baseline to post-intervention. Changes in mindfulness, self-compassion and worry were found to significantly mediate the effects of MBSH versus both control conditions on changes in stress. Findings suggest that cultivating mindfulness specifically confers benefits to stress and that these benefits may occur through improving theorised mechanisms.