Touching a tree does not electrically ground you the way stepping barefoot onto wet soil does. Tree trunks are made of wood, and wood is a poor electrical conductor. The resistivity of living tree stems is high enough that the tiny currents involved in “earthing” would struggle to pass through bark and sapwood to reach the soil below. That said, touching a tree can produce real, measurable physiological effects through entirely different pathways, and those effects are sometimes confused with the electrical grounding that wellness communities promote.
What “Grounding” Means in This Context
Earthing, or grounding, is the practice of making direct skin contact with the Earth’s surface, usually by walking barefoot on grass, soil, or sand, or by using conductive pads connected to a grounded electrical outlet. Proponents argue that this contact allows electrons from the Earth to flow into the body, reducing inflammation and stabilizing the body’s electrical environment. The concept has attracted a small but dedicated research community. One review described it as “the discovery of benefits, including better sleep and reduced pain, from walking barefoot outside or sitting, working, or sleeping indoors connected to conductive systems that transfer the Earth’s electrons from the ground into the body.”1PubMed Central. Earthing: health implications of reconnecting the human body to the Earth’s surface electrons
The electrical part of this claim is straightforward physics. When you stand barefoot on damp earth, you and the ground reach the same electrical potential. One study showed that connecting the body to earth through a copper conductor caused a rapid drop in the body’s electrostatic potential to roughly −200 millivolts, an effect that reversed immediately when the connection was broken.2PubMed. Earthing the human organism influences bioelectrical processes Whether that voltage shift produces meaningful health effects is debated, but the shift itself is real. The question is whether a tree trunk can serve as the conductor.
Why a Tree Trunk Is Not a Good Conductor
Wood has high electrical resistivity. A survey of temperate forest species found that tree resistivity was roughly 200% higher than the resistivity of vines, and conifers were about 135% more resistive than hardwoods.3Canadian Journal of Forest Research. Electrical properties of temperate forest trees: a review and quantitative comparison with vines The resistivity also varies with moisture content, species, and even measurement height on the trunk. Coniferous trees like spruce and pine tend to have more uniform but still highly resistive internal patterns, while broadleaf species like beech show complex variability driven by wood density.4Tree Physiology. Electrical resistivity tomography: patterns in Betula pendula, Fagus sylvatica, Picea abies and Pinus sylvestris
Bark adds another layer of insulation. The outer bark of most trees is dead tissue with very little moisture, making it an even worse conductor than the sapwood beneath it. And the bulk electrical conductivity of living stems is remarkably low. Measurements of tree stem conductivity under salinizing irrigation found values in the range of 2–10 × 10⁻² deciSiemens per meter, with the lower values appearing after installation wounds healed and intact cell membranes restored their insulating effect.5Soil Science Society of America Journal. Relations between Soil and Tree Stem Water Content and Bulk Electrical Conductivity under Salinizing Irrigation For context, damp soil is far more conductive than this. Your hand pressing against bark is making contact with one of the more resistive natural materials around.
Trees do conduct electricity along their root systems. Research on root-to-soil interfaces has confirmed that electric current flows between roots and soil through the same pathways that water uses.6Tree Physiology. Electrical measurement of the absorption surfaces of tree roots by the earth impedance method: 1. Theory But that current flows deep underground through moist root tissue, not up through dry bark to your palm. A lightning bolt can force its way through a tree because it carries enormous voltage. The tiny nanoampere-scale currents involved in human earthing cannot overcome wood’s resistance in any meaningful way.
How Small the Electrical Exchange Actually Is
Even when you ground yourself directly to the earth through a proper conductive connection, the currents are minuscule. A study that measured the charge exchange between the human body and ground found currents in the nanoampere range, and those currents correlated with subject motion rather than carrying any biologically meaningful signal.7PubMed Central. Analysis of the charge exchange between the human body and ground: evaluation of “earthing” from an electrical perspective If the currents through a direct, low-resistance earth connection are already that small, the currents through a high-resistance tree trunk would be orders of magnitude smaller still, effectively zero for practical purposes.
This is worth emphasizing because many wellness guides treat trees as natural grounding rods. Electrically, they are not. A tree’s root system is grounded, yes, but the trunk between you and those roots acts more like a wooden fence post than a copper wire. If your goal is specifically electrical earthing, bare feet on wet grass will accomplish far more than hugging a tree.
What Touching a Tree Actually Does to Your Body
Here is where the picture gets more interesting. Even without an electrical pathway, touching wood has measurable physiological effects. A series of controlled experiments compared the response to touching white oak with the response to touching marble, tile, and stainless steel. Participants who touched uncoated white oak showed a significant increase in parasympathetic nervous system activity compared to those touching marble or stainless steel.8PubMed Central. Physiological Effects of Touching Wood The parasympathetic nervous system is the branch responsible for the “rest and digest” state, so a boost in its activity reflects genuine calming.
A follow-up study tested whether coatings changed this effect and found that they did. Uncoated wood and wood with an oil finish both increased parasympathetic activity, but wood sealed with urethane, vitreous, or mirror finishes did not.9PubMed Central. Physiological Effects of Touching Coated Wood The implication is that the natural texture and possibly the warmth and slight give of bare wood matter for this effect. Once you seal the surface with plastic-like coatings, the calming response disappears.
Testing this with a specific tree species, researchers found that touching hinoki cypress wood with the palm calmed prefrontal cortex activity and increased parasympathetic nervous activity compared to touching marble.10Journal of Wood Science. Physiological effects of touching hinoki cypress (Chamaecyparis obtusa) These studies used cut wood samples rather than living trees, so the effect appears to be driven by the tactile properties of wood itself, not by any electron transfer from the earth. The warmth, texture, and slight compliance of natural wood trigger sensory pathways that cold, hard, smooth materials do not.
When you place your hand on a living tree, you are getting these tactile benefits plus whatever additional sensory input comes from the bark texture, temperature, and the outdoor environment. None of this requires electrical grounding. Your nervous system is responding to touch, not to electrons.
The Phytoncide Effect and Why Trees Help Even Without Contact
Trees release volatile organic compounds called phytoncides, chemicals that evolved to protect them against insects and pathogens. These same airborne molecules appear to affect human immune function. Exposure to tree-derived phytoncides significantly increased natural killer cell activity and the number of cells expressing cancer-fighting proteins like perforin and granzymes, while decreasing stress hormones adrenaline and noradrenaline in urine.11PubMed. Effect of phytoncide from trees on human natural killer cell function
This effect does not even require a forest. A randomized trial tested phytoncide essential oil exposure on gynecological cancer survivors in an indoor setting and found that the phytoncide group showed significant increases in natural killer cell levels after eight weeks, along with reduced psychological stress. The researchers attributed the changes to shifts in parasympathetic nerve activity and cortisol levels.12PubMed Central. Effects of phytoncide on immune cells and psychological stress of gynecological cancer survivors: randomized controlled trials In other words, simply breathing near trees can produce health benefits that have nothing to do with electrical grounding. When someone hugs a tree and feels better, phytoncides and the calming effect of natural touch are more plausible explanations than electron flow.
The State of Earthing Research
The broader earthing literature deserves some honest assessment. There are real findings, but they come with significant caveats. Several small studies have reported that grounding the body during sleep reduces nighttime cortisol and shifts its secretion toward a more normal circadian rhythm.13PubMed. The biologic effects of grounding the human body during sleep as measured by cortisol levels and subjective reporting of sleep, pain, and stress Other research has reported that grounding produces measurable changes in white blood cell counts, cytokine concentrations, and other inflammatory markers.14PubMed Central. The effects of grounding (earthing) on inflammation, the immune response, wound healing, and prevention and treatment of chronic inflammatory and autoimmune diseases One study found that grounding increased the surface charge on red blood cells and reduced blood clumping.15PubMed Central. Earthing (grounding) the human body reduces blood viscosity—a major factor in cardiovascular disease
These findings are intriguing, but the studies tend to be small, often lack rigorous blinding, and many come from a tight-knit group of researchers with commercial ties to earthing products. Large, independent, pre-registered clinical trials are essentially absent from the literature. The mechanism by which nanoampere currents could cause systemic anti-inflammatory effects remains unexplained in any physics-consistent way. That does not mean the observed effects are fake; it means we cannot yet distinguish between a genuine electrical mechanism and the combined influence of relaxation, time spent outdoors, placebo effects, and the simple act of lying still with attention to your body.
One finding that holds up well regardless of mechanism is that grounding the body reduces AC body voltage from ambient electromagnetic fields by about 58-fold.16PubMed. Effects of Grounding on Body Voltage and Current in the Presence of Electromagnetic Fields This is basic electrical engineering: connecting yourself to earth drains off the voltage induced by nearby wiring and appliances. Whether that voltage reduction matters for health is a separate question, but the voltage drop itself is real and large. A tree, again, would not accomplish this effectively because the trunk’s resistance would prevent the voltage from draining to ground.
Why People Confuse Tree Benefits with Electrical Grounding
Spending time among trees genuinely does reduce stress hormones, boost immune markers, lower blood pressure, and improve mood. The evidence for those effects is solid and comes through multiple pathways: phytoncides in the air, the tactile experience of natural materials, reduced noise exposure, visual processing of natural scenery, and physical activity. When someone presses their palms against a tree and feels calmer, something real is happening. The error is in attributing that calm to an electrical connection rather than to the sensory experience.
The earthing community has, perhaps inadvertently, co-opted the legitimate benefits of nature contact and rebranded them under an electrical framework that does not hold up for tree contact specifically. Walking barefoot in a forest will ground you electrically through the soil while simultaneously exposing you to phytoncides and natural textures. But if you are standing in shoes and touching a tree trunk, the only pathways available are sensory, chemical, and psychological. The electrons are not getting through.
What About Wet Bark or Mossy Trees
Moisture changes the picture somewhat. Water dramatically lowers the resistivity of wood, and a soaking-wet or moss-covered tree trunk will conduct better than a dry one. The research on tree resistivity shows that moisture content is a primary driver of conductivity, particularly in conifers.4Tree Physiology. Electrical resistivity tomography: patterns in Betula pendula, Fagus sylvatica, Picea abies and Pinus sylvestris A tree in a rainstorm, with water running down the bark and saturating the outer layers, would be meaningfully more conductive than a tree on a dry summer day.
Even so, the path from your hand to the root zone is long. A tall tree might put 10 to 20 meters of wood between your palm and the soil, and even wet wood remains far more resistive than a simple copper wire or a patch of damp grass underfoot. If you are standing in a rainstorm touching a wet tree, the puddle under your bare feet would ground you far more effectively than the tree itself.
If You Want the Benefits, Here Is What the Evidence Supports
For electrical grounding specifically, the research points to direct skin-to-earth contact as the effective method: bare feet on grass, sand, soil, or concrete (which is conductive because of its mineral content and moisture). Grounding mats and sheets connected to a building’s grounding system also work because they provide a low-resistance path to earth. Touching a tree does not reliably provide this.
For the broader calming and immune-boosting effects people associate with trees, the evidence suggests several independent mechanisms that do not require any electrical connection:
- Touch: Contact with natural, uncoated wood activates parasympathetic nervous activity in a way that synthetic or mineral surfaces do not.
- Airborne chemistry: Phytoncides released by trees boost natural killer cell activity and reduce stress hormones, and this works even indoors with essential oils.
- Sensory environment: The combination of natural sounds, visual complexity, reduced artificial light, and fresh air creates a restorative sensory context.
These mechanisms are all well-documented and do not depend on unproven electron-transfer claims. You can get the tactile benefit from pressing your palms to a tree trunk. You can get the phytoncide benefit from breathing deeply in a pine forest or even diffusing tree-derived essential oils at home. And you can get the electrical grounding benefit separately by taking off your shoes and standing on the earth. Conflating all three into a single “tree grounding” narrative is where the popular wellness advice goes wrong.
Trees and Soil Microbes
One underappreciated aspect of spending time near trees is exposure to soil microorganisms. The soil around tree roots is teeming with bacteria, fungi, and other microbes, and some of these appear to have direct effects on stress physiology. Research on one soil bacterium, Mycobacterium vaccae, has shown that exposure to it shifted mice toward more proactive stress-coping behaviors and, in combination with certain environmental conditions, improved cognitive function. The bacterium also stabilized the gut microbiome and counteracted stress-induced reductions in microbial diversity.17PubMed Central. Effects of Immunization With the Soil-Derived Bacterium Mycobacterium vaccae on Stress Coping Behaviors and Cognitive Performance in a “Two Hit” Stressor Model
This is animal research, and extrapolating directly to humans sitting under a tree requires caution. But it adds another non-electrical pathway through which close contact with trees and their surrounding soil environment could influence health. Gardeners, hikers, and people who spend time in forests are inhaling and touching soil microbes constantly. Whether these exposures help explain the health benefits of nature contact in humans is an active area of research. It is, at least, a more biologically plausible mechanism than nanoampere currents flowing up through several meters of tree trunk.