Airo fundamentally works by measuring the state of your nervous system.
Heart Rate Variability (HRV) - not to be confused with Heart Rate (HR) - is the measure of beat to beat differences in your heart rate.
If your heart is beating at 60 beats per minute, It doesn’t mean you have 1 beat per second (as shown in image below). The duration of each beat differs depending on the activity of your sympathetic and parasympathetic nervous systems. The sympathetic nervous system fires when you are in a "fight-or-flight" situation whereas the parasympathetic nervous system fires when you need the “rest and digest" situation. During the course of a day, your body is constantly going back and forth between these two systems depending on what situation you encounter. Your sympathetic nervous system responds to the stressors on your body and mind such as physical activity, overweight, depression, and everyday stress. Your parasympathetic nervous system is responsible for helping your body recover from that stress.
Ideally, you want a flexible system that is able to fight or recover as needed but the busyness of our lives has evolved far beyond what our bodies are not designed for. It is now more important than ever to keep keep the body and mind in balance. The higher your HRV, the more your body is capable of adapting to change. Lower HRV shows your body is going through stress. Heart rate variability is a measurement that quantifies the sympathetic and parasympathetic activities in your body; or in other words, it represents the stress and recovery your body experiences. The HRV tracker uses Root Mean Square of Successive Differences (RMSSD) to measure HRV.
Even though the value of HRV has been known for the past thirty years, it is only in the past decade that technology has caught up to it. It is only now that HRV can be tracked continuously without being strapped to wires. HRV has is actively used in several fields including fitness training, weight-loss, psychotherapy, and also has clinical use for cardiac patients.