Effect of nature exposure on perceived and physiologic stress: A systematic review.

OBJECTIVE: The purpose of this systematic review is to evaluate the effect nature exposure has on stress as measured by physiologic markers and self-report. DESIGN: Researchers searched PubMed and JSTOR. Randomized control trials and cross-sectional studies were included if they met the following criteria: 1) included a clinical cohort and controls, and the intervention was nature exposure, either real or simulated; (2) utilized measurements of sympathetic activity or perceived stress; (3) study population consisted of greater than thirty male and female volunteers. Twelve studies were included for data extraction and review. SETTING: Researchers conducted this review at University of South Florida Morsani College of Medicine. MAIN OUTCOME MEASURES: Researchers measured perceived stress through the Perceived Stress Scale (PSS) and Depression, Anxiety, and Stress Scale (DASS). Physiologic stress was measured by salivary cortisol, blood pressure (BP), subgenual prefrontal cortex (sgPFC) activation on functional magnetic resonance imaging (fMRI), skin conductance level (SCL), heart rate variability (HRV), muscle tension, heart period, pulse transit time, amygdala and pregenual anterior cingulate cortex (pACC) activation on fMRI, respiratory sinus arrhythmia (RSA), and pre-ejection period (PEP). RESULTS: This review found an inverse relationship between nature exposure and various physiologic markers of stress in all 7 studies measuring physiologic stress. Perceived stress was also affected by higher exposure to nature as indicated by lower self-reports on the PSS and DASS in 5 out of 6 studies measuring perceived stress. CONCLUSIONS: Nature exposure has been widely shown to have a positive effect in reducing stress, both perceived and physiologic