Stress is a major health problem in today's workplace. Recent studies suggest that acceptance and commitment therapy (ACT) is effective for reducing stress at work, specifically among managers. Moreover, smartphone-delivered treatments have been developed and increasingly used in research. The objective of our study was to evaluate the efficacy of an ACT-based smartphone treatment among middle managers at medium- and large-sized companies (>50 employees) in Sweden. A total of 73 participants were randomized to either receive the six-week stress intervention (n =36) or to a waitlist control group (n =37). Results showed small to moderate within-group effect sizes (Cohen's d range 0.37–0.62) for the treatment group, and small to moderate between group effects (Cohen's d range 0.41–0.50). In conclusion, the study indicates that a smartphone administered stress intervention based on ACT can reduce perceived stress and increase general health among Swedish middle managers in the private sector. 
Stress management for middle managers via an acceptance and commitment-based smartphone application: A randomized controlled trial