A review of studies in environmental psychology and neuroscience suggests that natural environments contain many of the necessary ingredients for restoring individuals fatigued from prolonged, focused mental effort. As such, time spent in nature can help reduce stress, mental fatigue and incidents of human error, while improving attention and level of effectiveness.
Kaplan, Stephen. (1995). The restorative benefits of nature: Toward an integrative framework. Journal of Environmental Psychology. 15(3): 169-182.