HeartQuest is the physiological phenomenon of variation in the time interval between heart beats. It is measured by the variation in the beat to beat intervals. We call this the time domain. A healthy heart rate variability is reflected by lots of variation in the time domain between successive heart beats. This would indicate a very robust autonomic nervous system. Someone with less variation between one heart beat to the next has low heart rate variability and indicates decreased autonomic nervous system regulation. The importance of Heart Rate Variability is that it is controlled by the autonomic nervous system and therefore is a window into its function. The autonomic nervous system automatically influences the visceral organs, smooth muscle such as the blood vessels and glands and is a big influence on the heart.
There are two branches to the autonomic nervous system: the Sympathetic nervous system and the Parasympathetic nervous system. The Sympathetic nervous system deals with the stress situations and is sometimes referred to as the fight or flight system. It is triggered by any stress such as conscious or unconscious psychoemotional stress, toxins and electromagnetic influences. The opposite is the Parasympathetic nervous system, which is involved in conserving energy and is highly involved with digestion.