«Too little sodium can also
increase sympathetic nerve activity, which raises the risk of heart attacks, and boost the secretion of aldosterone, a hormone produced by the adrenal gland that is bad for the cardiovascular system.»
The researchers found significant residual effects, with neither heart rate variability or
sympathetic nerve activity returning to the baseline 15 minutes after the TENS machine had been switched off.
They measured blood pressure, performed an electrocardiogram (EKG), and
recorded sympathetic nerve activity directly in real - time using electrodes placed inside a large nerve.
One study on forest bathing revealed that forest environments promote lower concentrations of cortisol, lower pulse rate, lower blood pressure, greater parasympathetic nerve activity, and
lower sympathetic nerve activity than do urban climes.
[1] R. Corti et al., «Coffee Acutely
Increases Sympathetic Nerve Activity and Blood Pressure Independently of Caffeine Content: Role of Habitual Versus Nonhabitual Drinking,» Circulation 106, no. 23 (2002): 2935 — 40.