In this study we investigated the value of flotation Restricted Environmental Stimulation Therapy (REST) as a stress-management tool. We focused on the physiological effects of REST, its influence on well-being, and on performance. Twenty-seven studies published in 25 articles or book chapters were included in a meta-analysis. The total number of participants was 449, with a mean age of 29 years (ranging between 20 and 45). Sixty-four percent was male and 36% was female. The results showed that REST has positive effects on physiology (e.g., lower levels of cortisol, lower blood pressure), well-being, and performance. The pre-post mean effect size and the overall randomized control group effect size were relatively strong. This suggests that despite some limitations of the original studies, flotation REST can be a useful stress management tool in addition to or instead of other stress management tools.