| ANS | autonomic nervous system |
| HPA | hypothalamus–pituitary–adrenal |
| HR | heart rate |
| HRV | heart rate variability |
| IPI | inter-pulse interval |
| PPG | photoplethysmography |
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.