# A Systematic Review and Meta-Analysis of EEG, fMRI, and fNIRS Studies on the Psychological Impact of Nature on Well-Being

## TL;DR

This review shows that spending time in nature improves well-being, especially by reducing negative emotions, and suggests future research should focus on diverse populations and brain health.

## Contribution

The study systematically reviews and meta-analyzes EEG, fMRI, and fNIRS data to quantify nature's psychological and neurophysiological benefits across populations.

## Key findings

- Nature exposure significantly reduces negative emotions in both healthy and clinical populations.
- Neurophysiological outcomes show a larger effect size than psychological outcomes in response to nature exposure.
- Most studies had methodological weaknesses, indicating a need for improved research standards in the field.

## Abstract

Public health relevance—How does this work relate to a public health issue?
A total of 33 studies, focused on understanding the psychological and physiological impact of nature on well-being, were identified, including a total of 2101 participants.Nature exposure decreased negative emotions in healthy and clinical populations, suggesting a therapeutic benefit that may support policies aimed at protecting and restoring natural environments to promote well-being.

A total of 33 studies, focused on understanding the psychological and physiological impact of nature on well-being, were identified, including a total of 2101 participants.

Nature exposure decreased negative emotions in healthy and clinical populations, suggesting a therapeutic benefit that may support policies aimed at protecting and restoring natural environments to promote well-being.

Public health significance—Why is this work of significance to public health?
In total, 23 studies were conducted in non-Western settings, highlighting a significant demographic gap and the need to include more research from Western environments.Only 1.4% of the participants were children, highlighting the need for more research on nature’s psychological and physiological impact in pediatric populations.

In total, 23 studies were conducted in non-Western settings, highlighting a significant demographic gap and the need to include more research from Western environments.

Only 1.4% of the participants were children, highlighting the need for more research on nature’s psychological and physiological impact in pediatric populations.

Public health implications—What are the key implications or messages for practitioners, policy makers and/or researchers in public health?
EEG studies should expand their scope to incorporate metrics like functional connectivity, while prioritizing the standardization of real-world data for study comparisons and the effective inclusion of AI.Future research should include different geographical and climate conditions as well as longitudinal data to assess the long-term impact of urban green spaces and natural environments on brain health and psychological well-being, while supporting the international neural exposome initiative.

EEG studies should expand their scope to incorporate metrics like functional connectivity, while prioritizing the standardization of real-world data for study comparisons and the effective inclusion of AI.

Future research should include different geographical and climate conditions as well as longitudinal data to assess the long-term impact of urban green spaces and natural environments on brain health and psychological well-being, while supporting the international neural exposome initiative.

Exposure to nature has been associated with benefits to human well-being, commonly evaluated using standardized psychological assessments and, more recently, neuroimaging modalities such as Electroencephalography (EEG), functional Magnetic Resonance Imaging (fMRI), and functional Near-Infrared Spectroscopy (fNIRS). This systematic review and meta-analysis addresses the following questions. (1) How is the impact of nature on well-being studied using psychological and neuroimaging modalities and what does it reveal? (2) What are the challenges and opportunities for the deployment of wearable neuroimaging modalities to understand the impact of nature on the brain’s health and well-being? A search on PubMed, IEEE Xplore, and ClinicalTrials.gov (March 2024) identified 33 studies combining neuroimaging and psychological assessments during exposure to real, virtual or imagined natural environments. Studies were analyzed by tasks, populations, neuroimaging modality, psychological assessment, and methodological quality. Most studies were conducted in Asia (n = 23 or 70%). Healthy participants were the dominant target population (70%). In total, 61% of the studies were conducted in natural settings, while 39% used visual imagery. EEG was the most common modality (82%). STAI (n = 8) and POMS (n = 8) were the most common psychological assessments. Only seven studies included clinical populations. Two separate meta-analyses of nine studies with explicit experimental and control groups revealed a significant positive effect of nature exposure on psychological outcomes (Hedges’ g = 0.30; p = 0.0021), and a larger effect on neurophysiological outcomes (Hedges’ g = 0.43; p = 0.0004), both with moderate-to-high heterogeneity. Overall, exposure to nature was associated with reductions in negative emotions in clinical populations. In contrast, healthy populations showed a more balanced psychological response, with nature exposure being associated with both increases in positive emotions and reductions in negative emotions. Notably, 88% of the studies presented methodological weaknesses, highlighting key opportunities for future neuroengineering research on the neural and psychological effects of nature exposure.