Psycho-Physiological Stress Recovery in Outdoor Nature-Based Interventions: A Systematic Review of the Past Eight Years of Research

Abstract

Background: In modern, urban daily life, natural environments are increasingly recognized as an important resource for stress recovery and general well-being.

Aim: the present review aims to provide an overview and synthesis of the past eight years' research into the psycho-physiological effects of outdoor nature-based interventions, related to stress recovery.

Method: a structured search was performed in seven databases, returning 5618 articles. Removal of duplicates and initial screening gave a total of 95 studies. After full text reading, 36 studies were included in the assessment.

Results: most of the psychological outcomes were related to different emotional measures. The synthesis of the results points towards outdoor, nature-based exposure having a positive effect on different emotional parameters, related to stress relief. The studies into physiological measures showed more equivocal results.

Conclusion: the research, conducted over the past eight years, into outdoor, nature-based exposure has now attained a sound evidence base for psychological and especially emotional effects, but the evidence base for physiological effects within this timeframe shows a great degree of heterogeneity.

Limitations: interpretation of the results is limited by the review only covering the past eight years' research on the subject.

Keywords: EPHPP quality assessment; cortisol; health-promoting environments; heart rate variability; mood; narrative synthesis; natural environments; self-estimated stress.

Figure 1

Flow diagram of article-selection process.

Figure 2

Synthesis of psychological outcomes of nature-based interventions. Number of studies with positive significant difference in pre-post measures of the nature intervention alone and/or effect of condition favoring the nature intervention. Number of studies with no significant difference found in pre-post measures of the nature intervention. Number of studies with positive significant difference in pre-post measures of both intervention and control and/or no significant difference between intervention and control. Note: some of the studies have several different measurement instruments and are thus represented in multiple columns in the figure.

Figure 3

Synthesis of physiological outcomes of nature-based interventions. Number of studies with positive significant difference in pre-post measures of the nature intervention alone and/or effect of condition favoring the nature intervention. Number of studies with no significant difference found in pre-post measures of the nature intervention. Number of studies with positive significant difference in pre-post measures of both intervention and control and/or no significant difference between intervention and control. Note: Some of the studies have several different measurement instruments and are thus represented in multiple columns in the figure.