Objective assessment of mental stress in individuals with different levels of effort reward imbalance or overcommitment using heart rate variability: a systematic review

Table 2 Overview of the HRV parameters evaluated in the review and their importance

HRV parameter	Definition and explanation	Activity as part of the autonomic nervous system
Time domain
SDNN [ms]	Standard deviation of all normal-to-normal R-R (NN) intervals	Sympathetic and parasympathetic nervous system
SDINN Index	Mean of the 5-min standard deviation of the NN interval	No clear assignment
SDANN [ms]	Standard deviation of the average of NN intervals in 5-min segments	No clear assignment
RMSSD [ms]	Root mean square of successive differences of NN intervals	Parasympathetic nervous system
pNN50 [%]	Percentage of successive NN intervals that differ by more than 50ms	Parasympathetic nervous system
Frequency domain
HF [ms²]	High frequency power	Parasympathetic nervous system
LF [ms²]	Low frequency power	Sympathetic and parasympathetic nervous system
LF/HF	LF/HF ratio	Quotient between LF and HF power

ISSN: 2046-4053