Grounding, HRV and the Autonomic Nervous System: What Does the Research Show?

What is HRV?

Your heart does not normally beat like a perfectly timed metronome.

Even at a steady average heart rate, the interval from one heartbeat to the next varies slightly. Heart rate variability describes this variation.

Those beat-to-beat changes are influenced in part by the autonomic nervous system—the system responsible for regulating many processes that happen without conscious effort, including heart rate, blood pressure, digestion and breathing.

Its two familiar branches are:

• the sympathetic nervous system, involved in mobilizing the body for action;
• the parasympathetic nervous system, including vagal influences that can slow cardiac activity.

But autonomic regulation is more complicated than a simple seesaw between "stress" and "relaxation."

Modern HRV guidelines emphasize that the two branches can change independently, together, or in more complex patterns. This matters when interpreting grounding studies.

What do HF, LF and LF/HF mean?

Researchers can analyze HRV according to different frequency bands.

High-frequency HRV (HF) largely reflects respiratory-linked changes in heart timing and is generally considered a useful indicator of cardiac parasympathetic influence.

Low-frequency HRV (LF) is more complicated. Older research sometimes treated LF as a marker of sympathetic activity, but current evidence indicates that it reflects a mixture of sympathetic, parasympathetic and other regulatory influences.

Similarly, the LF/HF ratio was once widely described as a measure of "sympathovagal balance." Current psychophysiology guidelines state that this interpretation is no longer considered tenable.

That distinction becomes important when we look at the grounding research.

The 2011 adult experiment: grounding versus sham grounding

One of the most directly relevant studies was published by Gaétan Chevalier and Stephen Sinatra in 2011.

The researchers recruited 28 relatively healthy adults, although one participant's data were excluded from the final HRV analysis, leaving 27.

Importantly, this was not simply a comparison between one grounded group and one control group.

Each participant completed two separate two-hour sessions and served as their own control. In one session they were genuinely grounded; in the other they underwent sham grounding. The order of the sessions was randomized.

Conductive electrode patches were placed on the palms of the hands and soles of the feet and connected, during genuine grounding, to an outdoor ground rod.

Each session contained three 40-minute periods:

40 minutes before grounding → 40 minutes grounded or sham-grounded → 40 minutes afterward.

What happened to HRV?

The clearest pattern involved high-frequency HRV.

Over the 40-minute intervention period:

• HF increased by approximately 63% during grounding;
• HF increased by approximately 33% during sham grounding.

The standard deviation of R-R intervals—reported as SDRR and broadly equivalent to SDNN—also increased more during grounding: approximately 50% compared with 20% during sham grounding.

LF increased as well: approximately 68% during grounding versus 28% during sham.

The HF finding is particularly interesting when viewed through modern HRV science, because HF HRV generally reflects cardiac parasympathetic effects.

However, LF should not now be interpreted simply as sympathetic or parasympathetic activity, and the study's LF/HF ratio remained essentially flat during the grounding period.

Why the study is interesting—and why it remains preliminary

The within-person sham-controlled design is a useful feature: the researchers were attempting to distinguish an effect of grounding from the relaxation that might occur simply from lying quietly for an extended period.

But there are important limitations.

The study was small. There were baseline differences between sessions that required normalization, and its statistical testing relied on very short, 10-second portions of the recordings at the beginning and end of the intervention periods. The researchers also conducted a large number of statistical tests.

One author, Gaétan Chevalier, was identified as a scientific consultant to Earth FX, a company associated with grounding products. The article does not provide a clear funding statement, so we cannot confirm from the paper who funded the study.

Even with those qualifications, the difference between the real and sham sessions makes the HF result worth further investigation.

Grounding and vagal tone in premature infants

A very different experiment was published by Passi and colleagues in Neonatology in 2017.

The researchers studied 26 stable premature infants at Penn State Health Hershey Medical Center. Skin voltage was measured in all 26, while usable HRV measurements were obtained from 20 infants.

The infants were electrically grounded using a skin electrode connected through a safety resistor to a dedicated ground outlet.

Researchers measured HRV before, during and after grounding.

A 67% increase in high-frequency HRV

Before grounding, mean HF power was 6.59 ms².

During grounding, it increased to 11.00 ms²—a rise of approximately 67%, which was statistically significant (p = 0.003).

After grounding was disconnected, HF fell to 6.14 ms², close to its pre-grounding level. The grounding-versus-post-grounding difference was also significant (p = 0.02).

LF power also increased significantly during grounding (p = 0.01).

At the same time, however:

• LF/HF did not change significantly;
• SDNN did not change significantly;
• heart rate did not change significantly.

That last point matters. The study did not find that every autonomic or cardiac measure moved in the same direction.

The electrical change happened immediately

The researchers also measured a 60-Hz electrical potential on the infants' skin.

Connecting them to ground reduced this measured skin voltage by more than 95%, from an average of about 415 mV to 19 mV.

So the study documented two separate observations:

What was directly measured: grounding dramatically reduced skin electrical potential, and HF HRV increased during the grounded period.

What remains uncertain: whether—and through what biological pathway—the electrical change caused the HRV change.

That distinction is important.

Can these findings be applied to adults?

Not directly.

Premature infants have developing autonomic nervous systems and were being studied in the unusual electrical environment of a neonatal intensive care unit.

The study also had no sham-grounding control condition. It used a before/during/after design, which makes the return of HF toward baseline after disconnection interesting, but it cannot exclude every alternative explanation.

The study therefore provides an intriguing physiological observation—not evidence that grounding will necessarily produce the same response in healthy adults.

The researchers reported NIH/NIDDK and University City Science Center salary support and stated that the funding sources had no role in the study's design, analysis or publication.

What happened with repeated grounding?

A 2018 exploratory study looked at 16 massage therapists over six weeks.

Participants spent the first week sham-grounded, the following four weeks grounded while working and sleeping, and the final week sham-grounded again. They were blinded to when the cords were genuinely conductive.

This study is useful because it asked a different question: rather than examining only an immediate response during a single grounding session, could repeated grounding be associated with lasting changes in HRV?

The results were much less clear.

There were some statistically significant differences within and between the study's two cohorts for HF, LF, SDNN and LF/HF. However, when the cohorts were combined, week-to-week changes in SDNN, LF, HF and LF/HF were not statistically significant.

The two cohorts also differed on several physiological measures despite randomization, complicating interpretation.

There is another important detail: the HRV periods used for these comparisons were recorded at times when participants were not actually grounded. The researchers were deliberately looking for possible longer-lasting effects rather than measuring the immediate response during electrical connection.

So this study does not provide a clean replication of the acute HF findings seen in the 2011 adult experiment or the infant study.

It suggests that longer-term autonomic effects, if they exist, remain considerably less certain.

The study was funded by Earth FX, grounding products were donated by earthing.com, and Chevalier disclosed consulting for Earth FX.

So does grounding activate the parasympathetic nervous system?

The evidence does not justify such a definitive statement.

What we can say is more precise—and still interesting.

Two acute human experiments found increases in high-frequency HRV during grounding. Modern HRV methodology supports HF HRV as an indicator of cardiac parasympathetic effects under appropriate conditions.

That makes a possible effect on parasympathetic cardiac regulation a reasonable research question.

But HRV is an indirect physiological measure. Neither experiment directly measured vagus nerve firing, and neither proves that grounding "activates the vagus nerve."

Likewise, phrases such as:

"switches off fight-or-flight"
"resets the nervous system"
"restores autonomic balance"

go beyond what these studies establish.

How might grounding affect HRV?

This remains unresolved.

Grounding researchers have proposed several mechanisms, including changes in body electrical potential, interaction with environmental electrical fields and broader effects involving electron transfer or physiological regulation.

The infant study provides particularly clear evidence that grounding can rapidly change measured skin electrical potential.

But demonstrating an electrical change at the body's surface is not the same as demonstrating the biological pathway responsible for an HRV change.

Similarly, hypotheses involving electrons and oxidative processes remain proposed mechanisms rather than established explanations for the HRV findings.

Future experiments would need to connect those pieces much more directly.

What does the research tell us so far?

Taken together, the human evidence offers an intriguing but early signal.

The 2011 adult experiment found greater increases in several HRV measures during grounding than during sham grounding, including a 63% increase in HF compared with 33% during sham.

The 2017 neonatal study reported a 67% increase in HF, followed by a return toward baseline after grounding stopped.

Those findings come from very different populations and protocols, which makes the similarity in the direction of the HF response interesting.

But three small studies are not enough to establish a reliable general effect. Larger adult trials using contemporary HRV methodology, robust sham controls and independent research teams would considerably strengthen the evidence.

The bottom line

Grounding research has produced measurable changes in heart rate variability, and the most interesting recurring observation in the acute studies is an increase in high-frequency HRV.

That matters because HF HRV is closely related to parasympathetic cardiac regulation.

The evidence does not yet show that grounding broadly "balances" the autonomic nervous system, activates the vagus nerve in a clinically meaningful way, or treats autonomic dysfunction.

What it does show is that the question is worth investigating.

Two small human experiments found notable HF-HRV changes during electrical grounding, while longer-duration findings remain less clear. The next step is larger, well-controlled adult research capable of determining whether the acute effect is reproducible, how long it lasts and what mechanism—if any—connects grounding to changes in cardiac autonomic activity.

For now, the evidence is preliminary, physiologically interesting and worthy of further study.

Research references

Chevalier G, Sinatra ST. Emotional Stress, Heart Rate Variability, Grounding, and Improved Autonomic Tone: Clinical Applications. Integrative Medicine. 2011;10(3):16–21.

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.

Chevalier G, Patel S, Weiss L, et al. Effects of Grounding (Earthing) on Massage Therapists: An Exploratory Study. Health. 2018;10:228–250. doi:10.4236/health.2018.102019.

Quigley KS, Gianaros PJ, Norman GJ, Jennings JR, Berntson GG, de Geus EJC. Publication Guidelines for Human Heart Rate and Heart Rate Variability Studies in Psychophysiology—Part 1: Physiological Underpinnings and Foundations of Measurement. Psychophysiology. 2024;61(9):e14604. doi:10.1111/psyp.14604.