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Selected HRV measures (Time domain measures)
| Parameter | Unit | Description |
|---|---|---|
| SDNN | ms | SD of all normal R wave (N-N) intervals |
| SDANN | ms | SD of all 5min average N-N intervals |
| SDNN index | ms | Mean of the SDs for 5 min segments |
| RMSSD | ms | Square root of mean of the sum of squares of successive N-N interval difference. Reflects vagal modulation |
| pNN 50% | Number of successive N-N intervals differing by >50ms divided by the total number of successive N-N intervals. Reflects vagal function |
