Table 2.

Advantages and disadvantages of short- and long-term spectral analysis of HRV.

	Advantages	Disadvantages
Short-term	•Easy to perform •Convenient to control the confounding factors •Needs less time for data processing •Can describe dynamic HRV change within a short period	•Not stable owing to the constant fluctuation of heart beat intervals •Cannot analyze ULF power
Long-term	•A stable tool for HRV analysis •Can analyze ULF power	•More expensive and time consuming •Include more noise •Influenced by activities and environmental factors

HRV, heart rate variability; ULF, ultra-low frequency component.