ACT-based self-help for perceived stress and its mental health implications without therapist support: A randomized controlled trial

Access to interventions that effectively reduce stress is limited and often costly. Lack of time, and stigma might also be significant barriers. This study examined the effectiveness of an Acceptance and Commitment Therapy (ACT)-based self-help book without therapist support for adults with moderate levels of stress, without psychiatric diagnoses. Participants were recruited primarily through the website of the book and posts in various social media channels. Participants (n = 133) were randomly assigned to an intervention group (n = 67) or a wait-list group (n = 66). Both the primary outcome measure (stress) and the secondary outcome measures (e.g., quality of life, worry, depressive symptoms and burnout symptoms) were measured before and after the intervention, and at 6-months follow-up. Compared to the wait-list group, the improvement was significantly larger in the intervention group at the end of intervention for stress (Cohen’s d = 1.00), worry (d = 0.69), and all three subscales of the burnout questionnaire (d = 0.59 to 0.73). The corresponding effect on depressive symptoms was medium (d = 0.51). We did not find any robust evidence of mediation of outcome through psychological flexibility or mindfulness, but number of pages read, number of mindfulness exercises performed, and perceived helpfulness of the weekly assignments significantly predicted change in stress. At the 6-month follow-up, the gains in the intervention group remained as the results were virtually identical to those at the end of intervention. Our findings provide additional support for the efficacy of an ACT-based pure self-help to reduce stress among adults with moderate level of stress, without psychiatric diagnoses. •We conducted an RCT of ACT-based pure self-help for stress compared to wait-list.•The intervention was aimed at adults with moderate levels of stress.•ACT resulted in significantly reduced perceived stress compared to wait-list.•Effect sizes were mostly medium to large.•The effects were maintained at 6-month follow-up.