Heart Rate Variability

     is a active topic of medical research, since correspondence between specific physiological components and the frequency spectrum has been shown. Specifically, these two components are the sympathetic and parasympathetic neural systems, which originate in the brain and effect organs throughout the body. The activity of the sympathetic system is heightened in situations that require a large but temporary expenditure of energy, such as the energy needed by the brain to process information while sledding down a steep slope through the woods, and adrenaline is often evidence of increased sypathetic activity. The the activity of the parasympathetic system is heightened during times of slow but continuous energy expenditure, such as when processing food in the stomach. The heart is also affected by these two systems, and as expected the sympathetic system speeds up the heart rate and the parasympathetic system slows down the heart rate. Heart rate variability is the result of the intricate interplay of these two systems.