Comparison of the effects of olfactory stimulation by air-dried and high-temperature-dried wood chips of hinoki cypress (Chamaecyparis obtusa) on prefrontal cortex activity

Recent studies have focused on the physiological relaxing effects of nature-derived stimulation [ 1 – 17 ], and there are several reports on the effects of wood odor on humans [ 9 – 11 ]. Miyazaki et al. [ 9 ] reported that inhalation of Taiwan hinoki oil odor decreases systolic blood pressure. In addition, Tsunetsugu et al. [ 10 ] found that the odor of Japanese cedar chips decreases systolic blood pressure and prefrontal cortex activity and that inhalation of α-pinene and limonene, which are major components of the wood odor, also decreases systolic blood pressure. Joung et al. [ 11 ] reported that inhalation of d -limonene enhances activity of the parasympathetic nervous system and decreases heart rate. Dayawansa et al. [ 16 ] found that inhalation of cedrol induces parasympathetic nerve activity and reduces sympathetic nerve activity. Furthermore, Bensafi et al. [ 17 ] reported a negative relationship between the subject’s heart rate and a subjective evaluation of feeling comfortable with olfactory stimulation using six essential oil components such as pyridine, l -menthol, and 1,8-cineole.