HRV and the Autonomic Nervous System
As the heart rate is controlled by the autonomic nervous system, the condition of the autonomic nervous system can be assessed through an analysis of the heart rate.
Many control systems of the body also try to reach their goal by changing the heart rate. Roughly, there are three frequency bands we can assign "strong" phenomenas:
- Low frequencies are closely linked to the sympathetic nervous system. Physical activity and temperature regulation are reflected in this band.
- Oscillations in the range of 0.1 Hz (periods of about 10 seconds) are mainly caused by the blood pressure regulation (baroreceptor-circle or baroreceptor reflex)
- High frequencies of around 0.25 Hz are associated with the parasympathetic nervous system. A high vagal tone shows a relaxing or recovering condition (eg. deep sleep).