Essential Oil of Japanese Cedar (Cryptomeria japonica) Wood Increases Salivary Dehydroepiandrosterone Sulfate Levels after Monotonous Work

Abstract

Employee problems arising from mental illnesses have steadily increased and become a serious social problem in recent years. Wood is a widely available plant material, and knowledge of the psychophysiological effects of inhalation of woody volatile compounds has grown considerably. In this study, we established an experimental method to evaluate the effects of Japanese cedar wood essential oil on subjects performing monotonous work. Two experiment conditions, one with and another without diffusion of the essential oil were prepared. Salivary stress markers were determined during and after a calculation task followed by distribution of questionnaires to achieve subjective odor assessment. We found that inhalation of air containing the volatile compounds of Japanese cedar wood essential oil increased the secretion of dehydroepiandrosterone sulfate (DHEA-s). Slight differences in the subjective assessment of the odor of the experiment rooms were observed. The results of the present study indicate that the volatile compounds of Japanese cedar wood essential oil affect the endocrine regulatory mechanism to facilitate stress responses. Thus, we suggest that this essential oil can improve employees’ mental health.

<b>Inhalation of Japanese cedar (</b><i><b>Cryptomeria japonica</b></i><b>) wood odor causes psychological relaxation after monotonous work among female </b><b>participants </b>

“…However, the interaction between experimental time and conditions did not significantly change in all biomarker levels. We previously found that DHEA-s levels increase in response to the inhalation of volatiles derived from Japanese cedar wood (17). The difference between the results of our previous and present studies may be attributed to physiological differences among the participants in the present study.…”

“…Caffeine consumption on the day of the experiment was prohibited. An experimental room in our research institute (17) was used. The specification of the experimental room is shown in Fig.…”

“…Each participant performed the experiment once in the absence (control treatment) or in the presence (wood treatment) of essential oil derived from Japanese cedar. We used Japanese cedar from Kitayama (Kyoto, Japan) as an experimental material and obtained essential oil (17). To measure psychophysiological effects, we filled a diffuser (Personal Diffuser Squair; AT-AROMA Co. Ltd., Tokyo, Japan) with a dilute solution containing Japanese cedar essential oil.…”

“…Each participant was supplied with a preprinted sheet of paper containing 15 lines of random, single-digit, horizontally aligned numbers. The participant was instructed to calculate the numbers of a specified line and to move to a new spectrometry (GC-MS) system were described in the previous study (17). We compared the collected GC-MS data with those retrieved from a mass spectral database library (NIST14) and calculated the concentrations of the target compounds in the sample using the calibration standard line of β-caryophyllene (Sigma-Aldrich).…”

“…We used five questionnaires for subjective evaluation. Three questionnaires for the subjective assessment of the odor of the experimental rooms were described in the previous study: irritation scale and hedonic scale, a visual analog scale (VAS) (17). And subjective fatigue was also measured with VAS: "does not feel tired at all-completely exhausted."…”