Table 1
Demographics of study participants
Variable | N | Percent |
Gender |
Male | 24 | 43.6% |
Female | 31 | 56.4% |
Education |
Undergraduate | 25 | 45.5% |
Graduate | 18 | 32.7% |
Postgraduate | 12 | 21.8% |
Marital status |
Single | 39 | 70.9% |
Married | 16 | 29.1% |
Occupation |
Employed | 29 | 52.7% |
Unemployed | 26 | 47.3% |
Socioeconomic |
Low | 1 | 1.8% |
Middle | 34 | 61.8% |
High | 20 | 36.4% |
Age | Mean | St. deviation |
| 26.163 | 6.88 |
Descriptive values for TEIQUE SF 30 |
Wellbeing | 5.187 | 1.082 |
Self-control | 4.296 | 0.932 |
Emotionality | 4.586 | 0.987 |
Sociability | 4.363 | 0.954 |
Total TEI | 4.647 | 0.789 |
Table 1 shows that most participants were females (56%) and undergraduates (45.5%). A majority were single (70.9%). Most participants were employed (52.7%) and belonged to the middle class (61.8%). TEIQue SF 30 respondents were the highest who marked item number 20, specifically 41.8%. Conversely, the lowest number of respondents who marked items is number 10, specifically 3.6%. Similarly, the mean and standard deviation of TEIQue SF 30 are reported in Table 1. The Cronbach's alpha coefficients for the TEI factors are found to be well-being (α = 0.76), self-control (α = 0.45), emotionality (α = 0.59), and sociability (α = 0.52). The overall TEI score, encompassing all factors, demonstrates high internal consistency with a Cronbach's alpha value of 0.86.
Table 2
a: One-way repeated measures of ANOVA for the time domain, frequency domain, and nonlinear HRV measures.
Time domain | F- value | P-value | \(\eta p2\) |
SDNN | 4.297 | 0.023* | 0.081 |
Frequency domain | F- value | P-value | Partial Eta Squared |
LF | 10.044 | 0.000* | 0.159 |
LF/HF ratio | 9.980 | 0.000* | 0.196 |
Frequency domain | Chi-squared statistics | P-value Asymp. sig | |
HF | 19.614 × | 0.000* | |
Non-linear | F-value | P-value | \(\eta p2\) |
SD2 | 7.855 | 0.002* | 0.136 |
SD2SD1ratio | 7.847 | 0.001* | 0.129 |
ApEn | 56.840 | 0.000* | 0.517 |
Dfaα1 | 21.637 | 0.000* | 0.286 |
Dfaα2 | 24.397 | 0.000* | 0.319 |
× represents the chi-squared value in the above table
*p < 0.05
Table 2a represents one-way repeated measures of ANOVA for the time domain, frequency domain, and nonlinear HRV measures.
A statistically significant difference in mean SDNN values across the three-time points (F = 4.297, df = 1.646, p = 0.023) was observed. The descriptive statistics for SDNN indicate an elevated value at stress induction time T2 (37.27 ± 13.04) compared to baseline T1 (33.78 ± 11.91). The pairwise comparisons also indicated a significant difference in SDNN from baseline to the induction phase − 3.49(CI: -6.67 to -0.305, p = 0.032) However, no significant difference was observed between SDNN values during recovery and at baseline 0.196 (CI: -1.889 to 2.281, p = 0.851).
For HF, (the Friedman test) reveals a significant difference between baseline and stress-inducing time points for the recorded value of HRV, χ2 (2) = 19.614, p = 0.000. Post hoc analysis with a Wilcoxinoxon signed-rank test was conducted with a Bonferroni correction (p < 0.05). A significant difference was observed between the mental stress-inducing task and baseline (Z = -4.926, p = 0.000) and during the recovery and stress induction time points (Z = -3.538, p = 0.000). The analysis of variance for LF shows a significant statistical difference (F = 10.44, df = 1.991, p = 0.000). Significant mean differences at different time points were observed between baseline and stress induction period − 0.018(CI: -0.027 to -0.008, p = 0.000), where the recovery phase also exhibits significant differences with stress induction time 0.019 (CI: 0.009 to 0.028, p = 0.000). A statistically significant LF/HF ratio difference across different time points (F = 9.980, df = 1.821, p = 0.000) was found. Post hoc analysis revealed a significant LF/HF ratio increase during the stress induction phase compared to baseline, induced by the mental arithmetic task 0.579 (CI: -0.844 to -0.315, p = 0.000). Furthermore, a significant difference was observed between baseline and the recovery period, with a substantial mean decrease − 0.437(CI: -0.675 to -0.198, p = 0.001). A significant difference between baseline and stress induction time − 6.173(CI: -10.24 to -2.105, p = 0.004) and stress induction time to recovery time 5.241(CI: 1.783 to 8.699, p = 0.004) was observed. A significant difference for SD2 SD1 ratio (F = 1.226, df = 1.709, p = 0.001) was found. The pairwise comparison shows a significant difference between the baseline and stress induction phase − 0.275(CI: -0.427 to -0.124, p = 0.001). A significant difference is also observed between stress induction time and post-induction period 0.174(CI: 0.016 to 0.332, p = 0.032). However, no significant difference between baseline and post-induction time points is observed − 0101(CI: − 0.210 to 0.007, p = 0.067). Post hoc pairwise comparisons indicated significant differences between time points T1 and T2 0.162(CI: 0.117 to 0.206, p = 0.000). An important difference in mean values was observed from the stress induction phase to the recovery period − 0.170(CI: -0.208 to -0.132, p = 0.000).
Table 2
b shows significant correlations between the TEI four factors and HRV measures at different time points.
VARIABLES | T1 | T2 | T3 |
r | p | r | p | r | p |
Well being |
Sdnn | 0.321 | 0.020 | x | x | 0.280 | 0.045 |
Pnn50% | 0.332 | 0.020 | x | x | 0.297 | 0.036 |
Stress index | -0.318 | 0.023 | x | x | -0.337 | 0.012 |
Hf | x | x | 0.348 | 0.012 | x | x |
LFHF ratio | x | x | -0.310 | 0.027 | x | x |
Sd2 | 0.328 | 0.016 | x | x | x | x |
Sd2sd1ratio | x | x | x | x | 0.279 | 0.039 |
Self control |
Lf | 0.321 | 0.017 | x | x | x | x |
Emotionality |
Sdnn | 0.306 | 0.028 | x | x | x | x |
Stress index | x | x | x | x | -0.297 | 0.028 |
Sd2 | 0.300 | 0.028 | x | x | x | x |
Dfaα2 | x | x | x | x | -0.319 | 0.019 |
Sociobility |
HF3 | x | x | x | x | -0.407 | 0.002 |
Table 2.b shows significant correlations between the TEI four factors and HRV measures at different time points. SDNN exhibited moderate positive correlations at T1 (r = 0.321, p = 0.020) and T3 (r = 0.280, p = 0.045); pNN50% displayed a significant positive correlation at T1 (r = 0.332, p = 0.020), and stress index demonstrated negative correlations at T1 (r = -0.318, p = 0.023) and T3 (r = -0.337, p = 0.012). Positive correlations between high frequency (HF) power and well-being at T2 (r = 0.348, p = 0.012), as well as negative correlations between the LF/HF ratio and well-being at T2 (r = -0.310, p = 0.027) were observed.
From the time domain, SDNN exhibited a moderate positive correlation at T1 (r = 0.306, p = 0.028), whereas the stress index shows a significant negative correlation at T3 (r = -0.297, p = 0.028). The Poincaré plot standard deviation perpendicular to the line of identity (SD2) showed a moderately positive correlation at T1 (r = 0.300, p = 0.028), indicating the potential involvement of nonlinear dynamics in heart rate variability in emotional experiences. The Detrended Fluctuation Analysis exponent alpha 2 (DFAα2) displayed a positive correlation at T3 (r = 0.319, p = 0.019) The stress index demonstrated a negative correlation at T3 (r = -0.297, p = 0.028). There are marked correlations between the HRV measures and self-control factor.
LF demonstrated a moderate positive correlation (r = 0.321, p = 0.017), and HRV measures significantly correlated with sociability factor. A strong negative correlation was observed (r = -0.407, p = 0.002), indicating a potential link between autonomic nervous system activity and sociability.