How long does a mindfulness‐based stress reduction program need to be? A review of class contact hours and effect sizes for psychological distress

The standard Mindfulness-Based Stress Reduction (MBSR) program requires 26 hours of class time, but some groups cannot commit to that. This review examined published studies of MBSR, some of which used fewer class hours, and found no significant correlation between the number of in-class hours and the effect sizes for psychological outcomes in either clinical or nonclinical samples. The finding suggests that abbreviated MBSR programs may be worthwhile for populations where reducing psychological distress is the goal and longer time commitments are a barrier. However, the standard format has the most empirical support, and class time may matter for other outcomes. The authors call for systematic empirical studies on this question.

Study at a glance

Abstract

The mindfulness-based stress reduction (MBSR) program was designed to be long enough for participants to grasp the principles of self-regulation through mindfulness and develop skill and autonomy in mindfulness practice. It traditionally consists of 26 hours of session time including eight classes of 2-1/2 hours and an all-day class. The circumstances of some groups exclude them from participating in this standard form and a number of trials have evaluated programs with abbreviated class time. If lower program time demands can lead to similar outcomes in psychological functioning, it would support their utility in these settings and might lead to greater participation. However, the effect of variation in class hours on outcomes has not been systematically studied. To obtain preliminary information related to this question we examined effect sizes for psychological outcome variables in published studies of MBSR, some of which had adapted the standard number of class hours. The correlation between mean effect size and number of in-class hours was nonsignificant for both clinical and nonclinical samples and suggests that adaptations that include less class time may be worthwhile for populations for whom reduction of psychological distress is an important goal and for whom longer time commitment may be a barrier to their ability or willingness to participate. However, the standard MBSR format has accrued the most empirical support for its efficacy and session time may be important to the development of other kinds of program outcomes. The result points to the importance of empirical studies systematically examining this question.