## 4 Discussion  
During the intervention program, the subject's RMSSD and SDNN were monitored every five minutes (Figures 1-4). The RMSSD and SDNN showed a similar trend in sessions 1, 3 and 4. Only at the second session did the SDNN fluctuate more dramatically compared to the RMSSD. Despite the similar trends in sessions 1, 3 and 4, the change variation of the SDNN in the identical session was much bigger than that of the RMSSD. With regard to monitoring the subject's state, the more variable factor, the SDNN, is more appropriate. The first 3 min of heart rate data in every session were not included as they were considered to reflect the stabilization of the subject. Despite of this stabilizing time, the coefficients of variation (CV) of the first RMSSD and SDNN (calculated on minute 8) in every session were 34.2% and 68.9%. The CVs of the RMSSD and SDNN right after the subject's trauma telling were 31.9% and 21.1%. This implies that it is inappropriate to compare the values with each other because of the fluctuation associated with the same event. Various researchers have recommended careful comparison of short-term HRV readings [46]. Therefore, we compared the change ratios of the HRV. The comparison revealed that trauma telling had a significant impact on the subject's psychological status, as evidenced by the observed abrupt negative emotion changes within five minutes of the trauma tellings and the 10% SDNN increase at the time of the trauma tellings (Figures 5-8). This suggests that reliving the traumatic event through self-reporting can affect the subject's ANS as well as inducing emotional distress. The abrupt negative emotion changes followed by the trauma tellings increased the SDNN by about 10.5%, which was about twice the average SDNN increase (4.5%) at the time of all the abrupt emotion changes. The abrupt emotion changes followed by the trauma telling appeared to regulate the subject's ANS to a greater extent. The occurrence of abrupt negative emotion changes had a notable impact on the SDNN, which increased by approximately 4.5% on average at the time of the negative emotion change (Figures 5-8). However, this increase was followed by a decrease of approximately 17% five minutes later, indicating a return to the subject's ordinary state. Furthermore, the stabilizing technique performed by the psychotherapist showed promising results in promoting autonomic flexibility. The change ratios of the HRV factors demonstrated an increase in SDNN by approximately 23% at the time of intervention, indicating a positive effect on the subject's physiological response. This suggests that the stabilizing technique may have helped the subject regulate their autonomic nervous system and to achieve a more balanced state. Additionally, the occurrence of abrupt positive emotion changes was observed to influence the HRV factors in different ways (Figures 5-8). While the RMSSD showed a considerable increase of around 25% at the time of positive emotion change, the other HRV factors exhibited decreases of under 10%. This indicates that the HRV factors may not be \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Before** & **After** &
\begin{tabular}{c} **10 Months** \\ **After** \\ \end{tabular} \\ \hline \multirow{4}{*}{IES-R-K (Full score: 88)} & Re-experiencing & 23 & 10 & 15 \\ \cline{2-4}  & Hyperarousal & 21 & 19 & 20 \\ \cline{2-4}  & Sleep, emotion, & 14 & 15 & 10 \\ \cline{2-4}  & Avoidance & 24 & 17 & 17 \\ \cline{2-4}  & Summation & 60 & 43 & 40 \\ \hline \hline \multicolumn{2}{c}{AIS} & 10 & 7 & 6 \\ \cline{2-4}  & & & \\ \end{tabular}
\end{table} 
Table 1: The scale change in the IES-R-K and AIS before, after, and 10 months after the proposed program (a lower score is more positive). highly sensitive to transient positive emotional fluctuations. Therefore, relying solely on the RMSSD as a real-time indicator during psychological counseling may not be reliable.