Open-label placebo treatment to improve relaxation training effects in healthy psychology students: a randomized controlled trial.

Placebos, that are administered with deception, can reduce stress and increase relaxation. The present study investigated an open-label placebo (OLP) to improve the effects of Progressive Muscle Relaxation (PMR) training. A total of 160 psychology students were randomly assigned to a 14-day PMR course with or without daily OLP treatment. The placebo was administered along with an explanation of placebo effects and the verbal suggestion that the OLP activates the body's natural relaxation response. The relaxation instructions for home practice were delivered via a smartphone app, which was also used for the evaluation of the exercises. The participants of the OLP group completed more PMR exercises (M = 9.75) than the group without a placebo (M = 8.15). The two groups did not differ in reported exercise-related changes in relaxation level. On average, the OLP group rated the effects of the placebo as very low and was characterized by a higher drop-out rate compared to the group without OLP. Some participants experienced the OLP as negative. In conclusion, factors that influence the acceptance of OLP treatment require further investigation.