Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Dr. Scott T. Gaynor

Second Advisor

Dr. Amy Naugle

Third Advisor

Dr. Amy Damashek

Fourth Advisor

Dr. Sara B. Custodio


Acceptance and Commitment Therapy, health psychology, ACT, brief interventions, health-related behavior change


The Centers for Disease Control and Prevention have identified physical activity, nutrition, and sleep as three key health-related behaviors that can help the prevention of chronic disease. Only a fraction of the population met the recommended guidelines across these domains. It is important to develop interventions that can be simultaneously focused, flexible, efficient, and efficacious as a means of impacting population health. This study examined the efficacy of a single 60-minute Acceptance and Commitment Therapy (ACT) session targeting health-related behavior change and compared it to an information-only wait-list (WL) control condition. Forty-five collegians (Mage = 22.35 [6.91], 78% female, 56% white) were asked to select one of the three health-related targets (physical activity, nutrition, or sleep) and were randomized to receive ACT (n = 22) or WL (n = 23). Measures were taken at baseline, immediately following the ACT session, and at 15, 30, and 60 days. The 30-day follow-up was the primary endpoint and at that time those in WL were offered ACT.

Results suggest that immediately following the ACT session there was a modest increase in confidence in making a change. By the 30-day follow-up, mean changes in targeted health-related behavior were statistically significantly greater in ACT versus WL on most measures (medium-large effects). The effects were largest and most consistent for those who focused on sleep, followed by medium-small effects on physical activity, and inconsistent effects on nutrition. The improvements noted in ACT at 30 days were largely maintained at 60 days, but those who newly received ACT at 30 days were not significantly improved by 60 days. This study adds to the limited research on ACT as a brief intervention for health-related behavior change in suggesting the single ACT session generally outperformed an information handout WL control.

Access Setting

Dissertation-Open Access