This study of human stress in the built environment included a literature review, a survey assessing user perceptions of building material naturalness, and an experiment to determine the human stress impacts of wood use in office-like environments. The literature review indicated the potential for natural materials to be used indoors to create healthy impacts for building occupants. The survey revealed wood was perceived as a natural material. The human stress study revealed improved stress responses in an office with oak furniture compared to an office with white furniture.