Smartphone Monitoring of Participants' Engagement With Home Practice During Mindfulness-Based Stress Reduction: Observational Study.

Background: Standardized mindfulness training courses involve significant at-home assignments of meditation practice. Participants' self-reported completion of these assignments has been correlated with treatment outcomes, but self-reported data are often incomplete and potentially biased. In addition, mindfulness teachers typically suggest that participants set aside a regular practice time, preferably in the morning, but the extent to which participants do this has not been empirically examined.