Why Some People Feel Geomagnetic Storms and Others Don't

If you spend any time in wearable-data communities — Oura, Apple Watch, Garmin — you’ll eventually meet two kinds of people. The first will tell you, with complete conviction, that they can feel a geomagnetic storm coming before NOAA posts the alert. The second will look at exactly the same data and say they’ve never noticed a thing.

Both of them are probably right.

Geomagnetic sensitivity is real, measurable, and one of the most consistent findings in modern heliobiology. It’s also one of the most individually variable. The average effect across a population is small. The effect on the most sensitive individuals within that population can be large enough to dominate their day. The effect on the least sensitive individuals is, essentially, zero. And the variance between those extremes is what makes the field hard to study with traditional population-average designs — and what makes per-user analysis the only way to know anything useful about yourself.

The variance is documented, not anecdotal

You don’t have to take this on faith. The same papers that established that geomagnetic activity affects HRV also documented that it doesn’t affect everyone equally.

Alabdulgader et al. (2018), the 72-hour continuous HRV study across 16 subjects over five months, did something most heliobiology studies don’t: they reported per-subject responses, not just group averages. The result was striking. The group-level effect of geomagnetic activity on autonomic tone was modest. The individual-level effects ranged from “no measurable response” to “the dominant single driver of day-to-day HRV variance” in different subjects. Same population. Same exposure. Wildly different physiological readouts.

Gurfinkel et al. (2022) found something similar in a much larger cohort. The headline numbers — a 14.7 ms drop in r-MSSD on high-Kp days — were a population average. The actual within-cohort distribution was wide. A subset of subjects accounted for most of the signal. Other subjects showed essentially no relationship.

Zilli Vieira et al. (2024), the cognitive function paper, reported the same pattern in a different physiological domain: a real effect on average, concentrated in a definable subgroup, indistinguishable from noise in others.

This is the actual pattern across modern heliobiology. The question isn’t whether responses vary across individuals — they unambiguously do. The question is who is in the sensitive subgroup, and why.

The strongest known modifier: cardiovascular reserve

The most consistent finding across the literature is that people with reduced cardiovascular reserve — older adults, people with cardiovascular disease, people on medications that limit autonomic flexibility — show larger responses to geomagnetic activity than healthy young adults. This is borne out at the population level: meta-analyses confirm acute myocardial infarction risk rises 1.3–1.5× during geomagnetic storms and stroke risk rises 1.25–1.6×, with the increases concentrated specifically in people with diabetes, metabolic syndrome, or prior cardiovascular disease.

This isn’t surprising once you understand the mechanism. Geomagnetic activity affects HRV through the autonomic nervous system: sympathetic tone rises modestly, parasympathetic tone drops, HRV decreases. In a young healthy adult, this is a small perturbation on a large reserve — you barely notice. In an elderly patient with coronary disease, the same perturbation lands on a much smaller reserve, and the practical consequences are larger. The cardiovascular literature also documents elevated platelet activation and blood coagulability during storms — the biochemical chain that turns autonomic load into clinical event risk in vulnerable people.

This is why the Russian cardiology school of the 1990s — Gurfinkel’s earlier work, Stoupel’s epidemiology — kept finding cardiovascular signal. They were studying populations where the signal was bigger. The chronobiology school at Minnesota (Halberg, Cornelissen) found similar patterns in HRV more broadly, but the effects were largest in the older subjects. When the same methods are applied to a healthy 25-year-old, the signal often falls below the noise floor.

For the practical question of “should I worry about this?” — the answer for a young, healthy, well-conditioned person is “probably not in a clinical sense.” For someone over 60 with established cardiovascular disease, the answer is “this is one more factor your physiology has to absorb, and on a day when several factors converge, it can be the one that tips a difficult day into a worse one.” Neither of these is dramatic. But they’re real.

Age, sex, and medication interactions

Beyond cardiovascular reserve, several other modifiers show up consistently:

Age. Even after controlling for cardiovascular disease specifically, older adults show larger responses than younger adults. The autonomic nervous system loses flexibility with age — HRV at rest decreases naturally — and the relative impact of any external perturbation grows.

Sex. The data here is messier. Some studies report larger effects in men, some in women, and the methodology often doesn’t distinguish the two carefully. There’s likely a real sex-linked component (sex hormones modulate autonomic tone) but the literature isn’t clean enough to make confident claims yet.

Cardiovascular medications. Beta blockers, in particular, blunt the autonomic response to almost everything — including geomagnetic activity. If you’re on a beta blocker, your HRV won’t move much regardless of what’s happening in the magnetosphere, which means the geomagnetic-sensitivity signal in your data will be smaller (or absent) even if you were physiologically sensitive before starting the medication. SSRIs, calcium channel blockers, and several other classes have related effects on autonomic measurement.

Chronic stress and sleep debt. People who are already running depleted respond more to additional perturbations. This is true of any stressor, not just geomagnetic — but it does mean that the same geomagnetic event might land harder during a stressful week than during a recovered one. The Cornelissen lineage at Minnesota documented this carefully across multiple studies.

Underlying mental health conditions. Some of the older heliobiology literature (and a substantial amount of speculative work) has reported associations between geomagnetic activity and mood disorders, particularly bipolar episodes. The post-correction evidence here is much weaker than the cardiovascular evidence; treat any claims in this area with caution.

Geography and altitude: small, real, often overstated

You’ll sometimes see claims that people at high geomagnetic latitudes — Iceland, northern Scandinavia, northern Canada — experience stronger biological effects from geomagnetic activity because the field disturbance is larger there. The physics half of that claim is correct. The biology half is at best lightly supported.

The literature on geographic variation in geomagnetic sensitivity is small and mixed. Some studies report stronger effects at higher latitudes. Some don’t. The signal, when present, is much smaller than the individual variation within any single location.

Altitude is similar. Cosmic-ray flux is higher at altitude — Denver gets meaningfully more than New York — and there’s a plausible mechanism by which this could matter. The biological evidence at the population level, however, is thin enough that we’d argue against making lifestyle decisions based on it.

Both effects are real enough to acknowledge and small enough that, for the practical question of whether you are sensitive, your individual physiology matters more than your zip code. (What is Kp? covers the geographic angle of the index itself in more detail.)

The mechanism question — where speculation lives

Here’s where the literature is honest about its limits. We know geomagnetic activity correlates with HRV changes in the populations described above. We have hypotheses about why. We do not have a worked-out cellular mechanism the same way we have for, say, how caffeine affects adenosine receptors.

The current candidate mechanisms include:

• Cryptochrome flux modulation. Cryptochromes are flavoprotein magnetoreceptors found in the retina and several other tissues. They’re well-established as the magnetoreceptive molecule birds use for navigation. Whether they play any role in human physiology is genuinely unknown. CRY1 and CRY2 polymorphisms vary substantially across the human population, and if cryptochromes are part of the geomagnetic-sensitivity pathway, individual genetic variation here would predict the individual variation we observe. If.
• Magnetite-based detection. Trace amounts of biogenic magnetite have been found in the human brain, including in the pineal gland. Whether the quantities are enough to mediate biological response to geomagnetic fluctuation is unclear. Plausible, unproven.
• Indirect autonomic stress. This is the most parsimonious explanation: geomagnetic activity correlates with several other environmental signals (low-frequency atmospheric pressure waves, electromagnetic interference) that the body’s stress-detection systems pick up, and the cumulative load matters. This doesn’t require any specific magnetoreceptor — it works through general stress physiology.

The honest summary: we have a measurable population-level correlation, plausible candidate mechanisms, and no settled answer. That uncertainty matters because it should make you appropriately skeptical of any single explanation. It should also make you appropriately skeptical of anyone who tells you they know exactly which kind of person is sensitive and why. We don’t, yet.

Why personal profiling beats population averages

If individual variation in geomagnetic sensitivity is this large, the practical implication is straightforward: population-average studies tell you about average effects, which won’t necessarily reflect your effects in either direction.

The 14.7 ms r-MSSD drop from Gurfinkel 2022 is a real population-average effect. Your personal effect could be 0 ms (no response). It could be 30 ms (much stronger than average). It could be in the opposite direction from the average for reasons we don’t yet understand. The only way to know is to look at your data over enough time to surface your specific signal.

This is exactly what the Heliobios Personal Sensitivity Profile does. It takes your wearable biometric history (HRV, sleep, resting heart rate, and so on) and tests it against the panel of space weather drivers (Kp, solar wind, cosmic ray flux, X-ray flux, and others), using the same kind of statistical safeguards modern peer-reviewed heliobiology applies.

The output is your personal sensitivity, not the population’s. It can tell you that solar wind speed moves your HRV but Kp doesn’t, or vice versa, or that nothing in our panel correlates with anything in yours. The honest answer is sometimes “we don’t see a signal in your data” — and that’s a useful thing to know, because it means you can stop wondering whether you’re sensitive and turn your attention to inputs that actually matter for you.

The point isn’t to convince you that you’re sensitive. The point is to figure out whether you are, and if so, to which drivers, with statistical rigor that the older heliobiology literature didn’t apply. The article on what to do once you know you’re sensitive covers the practical next step.

What to take from this

If you’ve ever felt that geomagnetic storms affect you — and you have a vague sense that the world is gaslighting you about it — the evidence is on your side. Some people are sensitive. The sensitivity is real, documented, and consistent across multiple independent research groups.

If you’ve never noticed geomagnetic activity affecting you — and you’ve been quietly skeptical of friends who insist they’re sensitive — the evidence is also on your side. Many people are not sensitive. Some of those people are correctly reading their own physiology. Both things can be true at once because the variance across individuals is the actual finding.

The honest path forward is to look at your own data with proper statistics and let the answer be whatever it is. We built Heliobios because the tools to do that for a non-specialist didn’t really exist. The Personal Sensitivity Profile is the part of the app that justifies its existence. Everything else is downstream of getting that one analysis right.

Heliobios is a wellness application. It does not diagnose, treat, cure, or prevent any condition. Heliobios reads how your body may respond to environmental conditions and surfaces your personal correlations. Used alongside your existing health practices, it can be one input among many in understanding how your body actually behaves day to day.

Sources

1. Alabdulgader A, McCraty R, Atkinson M, et al. Long-term study of heart rate variability responses to changes in the solar and geomagnetic environment. Sci Reports. 2018;8:2663. https://www.nature.com/articles/s41598-018-20932-x
2. Gurfinkel YI, Vasin AL, Sasonko ML, et al. Geomagnetic storm under laboratory conditions: randomized experiment. Sci Total Environ. 2022. https://pmc.ncbi.nlm.nih.gov/articles/PMC9233046/
3. Zilli Vieira CL, Garshick E, Schwartz J, et al. Geomagnetic and solar activity associations with cognitive function. Sci Total Environ. 2024. https://www.sciencedirect.com/science/article/pii/S0160412024002526
4. Cornelissen G, Halberg F. Chronomedicine. In: Comprehensive Human Physiology. Springer; 1996. (Foundational reference for HRV-geomagnetic research lineage and individual-variation framing.)
5. Stoupel E. The effect of geomagnetic activity on cardiovascular parameters. Biomed Pharmacother. 2002;56 Suppl 2:247s–256s.
6. Palmer SJ, Rycroft MJ, Cermack M. Solar and geomagnetic activity, extremely low frequency magnetic and electric fields and human health at the Earth’s surface. Eur J Appl Physiol. 2020. https://pubmed.ncbi.nlm.nih.gov/32306151/

Heliobios is a wellness application operated by MALENTI LLC. It is not a medical device and is not intended to diagnose, treat, cure, or prevent any condition. See our Privacy Policy and Terms of Use.