Changes in State Mindfulness are the Key to Success in Mindfulness Interventions: Ecological Momentary Assessments of Predictors, Mediators, and Outcomes in a Four-Week Koru Mindfulness Intervention.

It is often assumed that changes in state mindfulness coupled with a decrease in intrusive thinking (e.g., rumination or worry) are the crucial ingredients in mindfulness interventions. We investigate this claim by examining within-person day-to-day changes and causal relationships among these changes in state measures of mindfulness, cognitive interference (a measure of intrusive thinking), depression, well-being, stress, sleep, physical activity, and quality of formal and informal mindfulness practice in a four-week randomized controlled mindfulness intervention with a sample of college students using the Koru mindfulness program; = 55 for intervention, = 57 for control; mean age = 21.4). The intervention was effective in improving day-to-day state mindfulness, cognitive interference, and sleep (the effects on all three were linear), but the effects on physical activity, depression, and well-being were not significant. Day-to-day mindfulness (the independent variable) was a predictor of change in daily cognitive interference (the mediating variable), which in turn predicted depression and well-being (dependent variables). The beneficial effects of state mindfulness were demonstrable over a lag of four days, suggesting it is indeed a key ingredient in the effectiveness of mindfulness interventions. Physical activity, sleep, and practice quality did not mediate any effects. One clear implication is that maintaining or restoring high levels of mindfulness, for instance by engaging in meditation or in more informal mindfulness exercises, would be of obvious and direct benefit to mental health and well-being.