Increase in salivary oxytocin and decrease in salivary cortisol after listening to relaxing slow-tempo and exciting fast-tempo music

Abstract

Relaxation and excitation are components of the effects of music listening. The tempo of music is often considered a critical factor when determining these effects: listening to slow-tempo and fast-tempo music elicits relaxation and excitation, respectively. However, the chemical bases that underlie these relaxation and excitation effects remain unclear. Since parasympathetic and sympathetic nerve activities are facilitated by oxytocin and glucocorticoid, respectively, we hypothesized that listening to relaxing slow-tempo and exciting fast-tempo music is accompanied by increases in the oxytocin and cortisol levels, respectively. We evaluated the change in the salivary oxytocin and cortisol levels of participants listening to slow-tempo and fast-tempo music sequences. We measured the heart rate (HR) and calculated the heart rate variability (HRV) to evaluate the strength of autonomic nerve activity. After listening to a music sequence, the participants rated their arousal and valence levels. We found that both the salivary oxytocin concentration and the high frequency component of the HRV (HF) increased and the HR decreased when a slow-tempo music sequence was presented. The salivary cortisol level decreased and the low frequency of the HRV (LF) to HF ratio (LF/HF) increased when a fast-tempo music sequence was presented. The ratio of the change in the oxytocin level was correlated with the change in HF, LF/HF and HR, whereas that in the cortisol level did not show any correlation with indices of autonomic nerve activity. There was no correlation between the change in oxytocin level and self-reported emotions, while the change in cortisol level correlated with the arousal level. These findings suggest that listening to slow-tempo and fast-tempo music is accompanied by an increase in the oxytocin level and a decrease in the cortisol level, respectively, and imply that such music listening-related changes in oxytocin and cortisol are involved in physiological relaxation and emotional excitation, respectively.

Conflict of interest statement

Competing Interests: Three of the authors are employed by a commercial company: NTT Corporation. This does not alter the authors' adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1. Experimental procedure and analysis of HR and HRV.

(A) Paradigm of Experiment 1. The participants experienced one 10-min silent period as a rest period, two saliva collection periods (1 and 2), each of which was 1–3 min long, and one 20-min music period. After the rest period, in saliva collection period 1 we took a saliva sample of over 3 mL from the participants for hormone assays. In the next music period, which lasted 20 min, a slow- or fast-tempo music sequence was presented. Finally, the participants again provided saliva during saliva collection period 2. The participants heard one of the slow- and fast-tempo music sequences on each day. The maximum sound pressure level of the music was regulated at 75 dB (A) in the slow mode. (B) A sample recording of the HR during baseline recording and music stimulation for 20 min. The HR was calculated with the following equation: HR (bpm) = 60*1000/R-R interval (ms). t = 0 indicates the start of the music. To evaluate the effect of music listening on the autonomic nerves, we analyzed the HR and HRV data in the t = 1080 to 1200 region (assessed region) and compared them with that at the baseline. (C) A sample analysis of HRV. Low-frequency (LF) and high-frequency (HF) components were obtained by integrating the power spectra over their respective ranges of 0.04–0.15 Hz and 0.15–0.40 Hz.

Fig 2. Effect of music stimuli on salivary oxytocin and cortisol levels.

(A) Salivary oxytocin level before and after 20 min of music stimulation. The salivary oxytocin level was greater after listening to the slow-tempo music sequence. (B) Salivary cortisol level before and after 20 min of music stimulation. The salivary cortisol level was lower after listening to the fast-tempo music sequence. Data are presented as means ± SEM; * p

Fig 3. Effect of music stimuli on indices of autonomic nerve activity.

(A) LnLF before and after music stimulation for 20 min. The main effect of Time was observed. (B) LnHF before and after music stimulation for 20 min. LnHF increased significantly after the participants listened to a slow-tempo music sequence. (C) LnLF/lnHF before and after music stimulation for 20 min. LnLF/lnHF increased significantly after the participants listened to a fast-tempo music sequence. (D) HR before and after music stimulation for 20 min. HR decreased significantly after the participants listened to a slow-tempo music sequence. Data are presented as means ± SEM; * p

Fig 4. Correlation between the change in the oxytocin level and changes in autonomic nerve activity.

(A-D) The change in the oxytocin level shows a significantly positive correlation with changes in (B) lnHF and a negative correlation with those in (C) lnLF/lnHF and (D) HR, while no significant correlation is observed between the change in oxytocin level and that in (A) lnLF. * p

Fig 5. Correlation between change in cortisol level and changes in autonomic nerve activity.

(A-D) The change in the cortisol level shows no significant correlation with changes in autonomic nerve activity (A-D). Pearson’s correlation coefficient r is described.

Fig 6. Correlation between the change in the oxytocin or cortisol level and self-reported emotions.

(A) Change in the oxytocin level vs arousal, (B) change in the oxytocin level vs valence, (C) change in the cortisol level vs arousal, and (D) change in the cortisol level vs valence. The change in the cortisol level vs arousal alone shows a significant correlation. * p