Grounding & The Vagal Response

Written By Robert Iron Shell

Vagal Tone

Vagal tone refers to the functional activity of the vagus nerve, the primary pathway of the parasympathetic nervous system. Originating in the brainstem, the vagus nerve innervates key organs including the heart, lungs, and digestive tract, modulating vital processes such as heart rate, respiration, and gastrointestinal motility.

The strength of vagal activity, its “tone,” is often assessed through heart rate variability (HRV), which reflects how efficiently the vagus nerve regulates cardiac rhythms. When vagal input is strong, the heart rate slows and variability increases. When vagal influence weakens, heart rate becomes more rigid and stress responses dominate.

Vagal Tone and Health

Higher vagal tone generally corresponds with improved cardiovascular function, greater resilience to stress, and reduced systemic inflammation. Conversely, low vagal tone is associated with impaired autonomic balance and numerous clinical disorders:

  • Heart Disease:
    Thayer et al. found that individuals with low vagal tone faced higher risk for cardiovascular disease, independent of common risk factors such as smoking or obesity [1].

  • Depression and Anxiety:
    Kemp and colleagues observed significantly reduced HRV in patients with depressive and anxiety disorders, suggesting diminished vagal regulation [2].

  • Inflammatory Bowel Disease (IBD):
    Bonaz et al. demonstrated lower vagal tone in IBD patients, proposing that impaired vagal modulation may exacerbate intestinal inflammation [3].

  • Alzheimer’s Disease:
    Chen et al. reported that vagus nerve stimulation could improve cerebral microvascular function, potentially enhancing cognition [4].

Across studies, vagal tone consistently appears as a marker of stress vulnerability [5]. Enhancing vagal activity, through electrical, behavioral, or conductive (grounding) means, may help counteract disorders driven by sympathetic overactivation.

Grounding and Vagal Tone

A 2017 study by Passi et al. examined whether grounding could improve vagal tone in premature infants within a neonatal intensive care unit (NICU) [6]. Conducted at Penn State Health Hershey Medical Center, the study involved 26 preterm infants and measured both skin voltage and HRV before and during grounding.

Prior research by Doheny et al. had shown that low vagal tone increases risk for necrotizing enterocolitis (NEC) [7–8], a severe inflammatory condition of the intestine in preterm infants. Grounding was hypothesized to enhance vagal tone and thus potentially mitigate this risk.

NICU Environment and Electromagnetic Fields

NICUs are saturated with low-frequency electromagnetic fields (ELF-EMFs) generated by incubators and medical equipment. The magnetic flux density (MFD) typically ranges from 2–100 milligauss (mG) [10–12]. Even at 2 mG, epidemiological studies have linked prenatal exposure to increased risk of asthma, obesity, and childhood leukemia [13–15].

Bellieni et al. observed that turning off power to an incubator caused an immediate rise in infants’ vagal tone, implying EMF exposure may suppress parasympathetic activity [18].

Passi’s Findings

Before grounding, the infants’ skin voltage averaged 415 ± 278 mV, reflecting 60-Hz electrical coupling from the incubator environment. Upon grounding, voltage dropped by over 95% to 19 ± 17 mV. Simultaneously, high-frequency (HF) power, the HRV component governed by parasympathetic activity, increased by 67%, indicating a substantial improvement in vagal tone.

Once grounding was discontinued, vagal tone returned to baseline. This immediate, reversible effect reinforced the link between skin potential and autonomic balance. Notably, measured MFD levels in this NICU were below 0.5 mG, much lower than in older incubator designs, showing that improved engineering had reduced EMF exposure [19].

Vagal tone sets the stage for understanding the body’s broader electrical and autonomic balance. Many downstream effects of grounding like lower inflammation, better cardiovascular stability, and calmer brain activity are rooted in restored vagal regulation.

By beginning with vagal tone, we establish the physiological foundation for upcoming topics: cortisol, stress, and sleep.

Stress activates the hypothalamic-pituitary-adrenal axis, increasing cortisol levels and sympathetic drive. Chronic stress weakens vagal tone, which in turn impairs our ability to regulate stress and sleep. Grounding’s ability to enhance vagal tone may thus be a key mechanism through which it stabilizes both the body and the mind.


References:

  1. Thayer, J. F., Yamamoto, S. S., & Brosschot, J. F. (2010). The relationship of autonomic imbalance, heart rate variability and cardiovascular disease risk factors. International Journal of Cardiology, 141(2), 122-131. DOI: 10.1016/j.ijcard.2009.09.543

  2. Kemp, A. H., Quintana, D. S., Felmingham, K. L., Matthews, S., & Jelinek, H. F. (2012). Depression, comorbid anxiety disorders, and heart rate variability in physically healthy, unmedicated patients: implications for cardiovascular risk. PloS One, 7(2), e30777. DOI: 10.1371/journal.pone.0030777

  3. Bonaz, B., Sinniger, V., Hoffmann, D., Clarençon, D., Mathieu, N., Dantzer, C., ... & Pellissier, S. (2016). Chronic vagus nerve stimulation in Crohn's disease: a 6-month follow-up pilot study. Neurogastroenterology & Motility, 28(6), 948-953. DOI: 10.1111/nmo.12806

  4. Chen X, He X, Luo S, Feng Y, Liang F, Shi T, Huang R, Pei Z, Li Z. Vagus Nerve Stimulation Attenuates Cerebral Microinfarct and Colitis-induced Cerebral Microinfarct Aggravation in Mice. Front Neurol. 2018 Sep 26;9:798. doi: 10.3389/fneur.2018.00798. PMID: 30319530; PMCID: PMC6168656.

  5. Porges SW. Vagal tone: a physiologic marker of stress vulnerability. Pediatrics. 1992 Sep;90(3 Pt 2):498-504. PMID: 1513615.

  6. Chevalier G, Sinatra ST. Emotional stress, heart rate variability, grounding and improved autonomic tone: clinical applications. Integr Med. 2011;10:16–21. 

  7. Doheny KK, Palmer C, Browning KN, Jairath P, Liao D, He F, Travagli RA. Diminished vagal tone is a predictive biomarker of necrotizing enterocolitis-risk in preterm infants. Neurogastroenterol Motil. 2014 Jun;26(6):832-40. doi: 10.1111/nmo.12337. Epub 2014 Apr 11. PMID: 24720579; PMCID: PMC4416658.

  8. Meister AL, Gardner FC, Browning KN, Travagli RA, Palmer C, Doheny KK. Vagal Tone and Proinflammatory Cytokines Predict Feeding Intolerance and Necrotizing Enterocolitis Risk. Adv Neonatal Care. 2021 Dec 1;21(6):452-461. doi: 10.1097/ANC.0000000000000959. PMID: 34847103; PMCID: PMC8638911.

  9. Applewhite, R. (2005). The effectiveness of a conductive patch and a conductive bed pad in reducing induced human body voltage via the application of earth ground. European Biology and Bioelectromagnetics, 1(1), 23-40.

  10. Bearer CF. Electromagnetic fields and infant incubators. Arch Environ Health. 1994 Sep-Oct;49(5):352-4. doi: 10.1080/00039896.1994.9954986. PMID: 7944566.

  11. Bullough J, Rea MS, Stevens RG. Light and magnetic fields in a neonatal intensive care unit. Bioelectromagnetics. 1996;17(5):396-405. doi: 10.1002/(SICI)1521-186X(1996)17:5<396::AID-BEM7>3.0.CO;2-Z. PMID: 8915549

  12. Cermáková E. Study of extremely low frequency electromagnetic fields in infant incubators. Int J Occup Med Environ Health. 2003;16(3):215-20. PMID: 14587534.

  13. Li DK, Chen H, Odouli R. Maternal exposure to magnetic fields during pregnancy in relation to the risk of asthma in offspring. Arch Pediatr Adolesc Med. 2011 Oct;165(10):945-50. doi: 10.1001/archpediatrics.2011.135. Epub 2011 Aug 1. PMID: 21810627.

  14. Ahlbom IC, Cardis E, Green A, Linet M, Savitz D, Swerdlow A. ICNIRP (International Commission for Non-Ionizing Radiation Protection) Standing Committee on Epidemiology: Review of the epidemiologic literature on EMF and health. Environ Health Perspect. 2001;109(suppl 6):911–933.

  15. Li DK, Ferber JR, Odouli R, Quesenberry CP Jr. A prospective study of in-utero exposure to magnetic fields and the risk of childhood obesity. Sci Rep. 2012;2:540. doi: 10.1038/srep00540. Epub 2012 Jul 27. PMID: 22844581; PMCID: PMC3406339.

  16. Johansson O. Disturbance of the immune system by electromagnetic fields-A potentially underlying cause for cellular damage and tissue repair reduction which could lead to disease and impairment. Pathophysiology. 2009 Aug;16(2-3):157-77. doi: 10.1016/j.pathophys.2009.03.004. Epub 2009 Apr 23. PMID: 19398310.

  17. Ahlbom IC, Cardis E, Green A, Linet M, Savitz D, Swerdlow A; ICNIRP (International Commission for Non-Ionizing Radiation Protection) Standing Committee on Epidemiology. Review of the epidemiologic literature on EMF and Health. Environ Health Perspect. 2001 Dec;109 Suppl 6(Suppl 6):911-33. doi: 10.1289/ehp.109-1240626. PMID: 11744509; PMCID: PMC1240626.

  18. Bellieni CV, Acampa M, Maffei M, Maffei S, Perrone S, Pinto I, Stacchini N, Buonocore G. Electromagnetic fields produced by incubators influence heart rate variability in newborns. Arch Dis Child Fetal Neonatal Ed. 2008 Jul;93(4):F298-301. doi: 10.1136/adc.2007.132738. Epub 2008 May 1. PMID: 18450804.

  19. Passi R, Doheny KK, Gordin Y, Hinssen H, Palmer C. Electrical Grounding Improves Vagal Tone in Preterm Infants. Neonatology. 2017;112(2):187-192. doi: 10.1159/000475744. Epub 2017 Jun 10. PMID: 28601861; PMCID: PMC5542808.

Robert Iron Shell
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Normal Is an Illusion: Why We Need Grounding