Abstract
OBJECTIVES: Duration, frequency, and intensity of nature exposure link to different physical and psychological benefits. The present study aimed to determine how time outdoors affected military veterans' posttraumatic stress disorder (PTSD) symptomology during PTSD treatment. METHOD: Hypotheses regarding time outdoors and the effect of program duration on PTSD symptoms were examined using multilevel models. The authors hypothesized that hours outdoors, both within- and between-persons, would predict reduced PTSD symptomology, program duration would predict reduced PTSD symptomology, and that hours outdoors and program duration would be significant when accounting for the other. RESULTS: The present study found that time outdoors correlated with participants' decreased PTSD symptomology: the more time participants spent outdoors, the greater the reduction in their PTSD symptoms. CONCLUSION: The effect of time outdoors was significant within-person, not between persons, suggesting that nature exposure may be used as an adjunct to traditional mental health treatment where exposure or dosage should be person-specific.