Physiological effects of touching hinoki cypress (Chamaecyparis obtusa)

Abstract

This study aimed to clarify the physiological effects of touching hinoki cypress (hereinafter called "hinoki") (Chamaecyparis obtusa) wood with the palm of the right hand on brain activity and autonomic nervous activity. Twenty-two female university students (mean age 21.1 ± 0.2 years) participated in the study. As an indicator of brain activity, oxyhemoglobin (oxy-Hb) concentrations were measured in the left/right prefrontal cortex using near-infrared time-resolved spectroscopy. Heart rate variability (HRV) was used as an indicator of autonomic nervous activity. The high-frequency (HF) component of HRV, which reflected parasympathetic nervous activity, and the low-frequency (LF)/HF ratio, which reflected sympathetic nervous activity, were measured. Plate (300 × 300 mm) of uncoated hinoki was used as tactile stimulation. Marble was used as a control material. After sitting at rest with their eyes closed, the participants touched the materials for 90 s with their eyes still closed. The results showed that tactile stimulation with hinoki significantly decreased oxy-Hb concentration in the left prefrontal cortex and increased ln(HF) reflected parasympathetic nervous activity compared with marble. In conclusion, our study showed that touching hinoki wood with the palm calms prefrontal cortex activity and increases parasympathetic nervous activity, thereby inducing physiological relaxation.

Positive physiological effects of touching sugi (Cryptomeria japonica) with the sole of the feet

“…Considering that we want to continue the previous studies [11][12][13][14]16], a total of 27 female Japanese university students (mean age: 21.9 ± 1.9 years) were included in the current study. None of the participants reported any physiological or psychiatric disorders in their personal histories, and all were non-smokers.…”

“…Conversely, very few reports regarding tactile stimuli were investigated. In response to this, recent research has begun to focus on the effects of tactile stimulation from wood by using the prefrontal cortex and autonomic nerve activity as indexes [11][12][13][14]. The physiological effects of palm contact with wood have been investigated for sugi (Japanese cedar, Cryptomeria japonica) [11], hinoki (Japanese cypress, Chamaecyparis obtusa) [12], and white oak (Quercus alba) [13,14].…”

“…In response to this, recent research has begun to focus on the effects of tactile stimulation from wood by using the prefrontal cortex and autonomic nerve activity as indexes [11][12][13][14]. The physiological effects of palm contact with wood have been investigated for sugi (Japanese cedar, Cryptomeria japonica) [11], hinoki (Japanese cypress, Chamaecyparis obtusa) [12], and white oak (Quercus alba) [13,14]. Touching with the palm of the hand in the sitting position for 90 s reduced prefrontal cortex activity, increased parasympathetic nervous activity, and decreased the heart rate compared to other types of building materials [11][12][13] and coated wooden materials [14]; thus indicating a state of physiological relaxation for the participants.…”

Physiological effects of visual stimulation with full-scale wall images composed of vertically and horizontally arranged wooden elements

“…In the present study, significant decreases in the oxy-Hb concentration were noted in the left and right prefrontal cortices. In the previous TRS studies using various sensory stimuli, significant differences were noted in only the left prefrontal cortex [34,37,50], only the right prefrontal cortex [33,35,39,40,51,52], or both cortices [36,38,[53][54][55]. Thus, it is not clear whether a significant decrease in the oxy-Hb concentration occurs in the right prefrontal cortex, left prefrontal cortex, or both cortices, and further investigations are needed in the future.…”

“…This finding suggests that NIRS enables the detection of brain activity in the prefrontal cortex region. Some previous studies reported that the oxy-Hb concentration in the prefrontal cortex significantly reduced and the subjective relaxed feeling significantly improved simultaneously in participants who had been exposed to visual [33][34][35], tactile [36][37][38], auditory [39], or olfactory [40] stimulation.…”