Improvements in Depressive Symptoms in Nature May Be Partly Caused by Improvements in Vagal Tone: A Review and Theoretical Perspective

Abstract

The positive effects of natural environments on mental health have been observed and studied for decades. Specifically, psychology research from across the world has suggested that nature can reduce depression symptomology, although there is uncertainty about the mechanisms behind this relationship. Scott, McDonnell, LoTemplio, Uchino, and Strayer proposed that cognitive restoration and stress recovery in nature are indications of stimulation of the vagus nerve. Applying Scott et al.'s argument to research on nature and depression, we argue that activation of the vagus nerve is part of the mechanism by which nature exposure decreases depression. Specifically, we review the evidence that causally links the vagus nerve to depression symptomology, and then review emerging evidence that nature improves vagal tone. More research on the direct relationship between being in nature and vagal tone in individuals with depression is needed to further understand this potential relationship. In addition, in an increasingly globalized world, it is vital that this research includes participants and researchers who are from different cultural backgrounds to determine whether this effect is present across humans from diverse backgrounds.