Determining the direction of prediction of the association between parasympathetic dysregulation and exhaustion symptoms

We tested the magnitude and directionality of the association between exhaustion symptoms and lnRMSSD via a multilevel cross-lagged panel model with covariates. Results are depicted in Table 2 and Fig. 1. We found that higher lnRMSSD meaningfully predicted lower exhaustion symptoms (b = − 0.16; 95% CI [− 0.29, − 0.04]). In contrast, the converse longitudinal association (lower exhaustion symptoms predicting higher lnRMSSD) was not meaningful (b = − 0.03; 95% CI [− 0.06, 0.00]), indicating an uni-directional association between lnRMSSD to exhaustion symptoms. The results were virtually identical for lnHF-HRV (Table 3): Mirroring the results of lnRMSSD, higher lnHF-HRV also meaningfully predicted lower exhaustion symptoms (b = − 0.06; 95% CI [− 0.12, − 0.00]). Also in line with the results for lnRMSSD, exhaustion symptoms did not meaningfully predict lnHF-HRV (b = − 0.06; 95% CI [− 0.12, 0.01]), emphasizing the importance of vmHRV predicting exhaustion symptoms.