Stress causes a very quick and significant decrease in white blood cell counts, creating a sudden state of immune vulnerability, such as may be caused by lack of sleep or travel. It also increases serum cortisol two to three-fold, a useful indicator of the level of stress. PEMFs increase host resistance by enhancing some immune functions. After exposure, neutrophils increase gradually and neutrophil metabolism and superoxide production are increased significantly. The cortisol level decreases.

Ascorbic acid (AA) is key to the antioxidant, neuroendocrine and immune mechanisms of stress adaptation (34). PEMFs cause ascorbic acid and serotonin to increase nearly two-fold by the 30th day of exposure. By the 90th day, ascorbic acid concentration returns to the initial (pre-exposure) value, while serotonin still remains significantly increased. This indicates that PEMFs may be useful in acute stress situations as well, by enhancing ascorbic acid function.

In athletes, PEMF therapy of the adrenal glands, thyroid gland or collar bone areas augments immune status and production of hormones, specifically, T-lymphocytes, testosterone and growth hormone and decreases circulating B-lymphocytes, cortisol and initially elevated levels of thyroid hormones. The athletes therefore have higher resistance to disease and higher work capacity.

In rabbits, emotional stress increases risk of sudden death. PEMFs increase resistance of the rabbits to stress. Death risk is lowered almost two-fold.

Pain is a major stressor. Pain inhibition has been consistently found by exposure to PEMFs in various species of animals, including: land snails, laboratory mice, deer mice, pigeons, as well as humans.

Heart rate variability (HRV) results from a complex interplay of neural and hormonal control mechanisms. Changes in HRV have been associated with increased risk of severe arrhythmia and sudden cardiac death in patients with recent myocardial infarction. Heart-rates (HR) are slowed. Some individuals may be more sensitive to or more consistent in having these PEMF-induced changes in HR and HRV. This effect appears to be due to changes to the cardiac pacemaker, the sino-atrial node, giving rise to a more normal beat-to-beat variability. Intermittent exposure daily is more effective than continuous exposure, e.g., overnight.

PEMFs and static magnetic fields (SMFs) act on carotid baroreceptors to reduce blood pressure by causing vasodilation and lowering heart rate. The stimulated baroreceptors reset sympathetic tone. The effects are thought to be due to changes in cell membrane calcium ion (Ca++) transport since they were abolished by verapamil, a potent Ca++ channel blocker. The effects may be of minimal clinical significance in healthy individuals but could be very significant in individuals with cardiovascular disease with abnormal HRV. In other work, strong SMFs had a parasympathetic or vagotonic action. Parasympathetic or vagotonic stimulation is stress reducing.

One group compared the effects of PEMFs and constant (static) magnetic fields on stress. Both weak PEMFs and SMFs (up to 100 gauss) were antitumorigenic, protective against toxic agents and Xray radiation and produced rejuvenation effects in states of stress.

Millimeter wave (MMW) PEMF exposure of an acupuncture point affects heart rate and heart rate variability and lability of the nervous system (NS) processes. Physical exercise increases lability of the nervous system (NS). Humans may naturally have predominance in their autonomic NS of either sympathetic or parasympathetic responses. With parasympathetic predominant people, exercise increases both heart rate and its variability. With sympathetic predominance, individual reactions to exercise vary greatly. MMW stimulation of selected acupuncture points helps recovery of heart rhythm changes after exercise in parasympathetic toned individuals, but not consistently in sympathetic predominance.