What are the most common units of measurement for heart rate variability?

The most common units of measurement for heart rate variability (HRV) are milliseconds. HRV is analyzed by measuring the time intervals between successive heartbeats, often referred to as inter-beat intervals (IBIs). These intervals are naturally oscillating and can fluctuate significantly; measuring them in milliseconds allows for a precise understanding of the autonomic nervous system's regulatory effects on heart function.

Using milliseconds helps in capturing the subtle variations in heart rate that occur in response to various physiological and emotional states. This granularity is essential for assessing the health and balance of an individual's autonomic nervous system, which can provide insights into stress levels, recovery status, and overall cardiovascular health. Other time measures like seconds, minutes, or hours are either too broad or not applicable to the specific analysis of heart rate variability, as HRV is inherently a measure of very short-term fluctuations.