The Surprising Link Between Solar Activity and Global Pandemics

Every so often a chart makes the rounds online: major flu pandemics plotted against the Sun’s sunspot count, the two lines rising and falling in suspicious lockstep. Sunspots and sickness, marching together. It gets passed around as the surprising link between solar activity and global pandemics, and it’s a tidy story. The question worth asking is whether it’s a true one.

Here’s where it actually lands. A handful of researchers have noticed major pandemics clustering near the Sun’s busiest and quietest years, and the idea is genuinely intriguing. But careful statistical work has not confirmed that solar activity causes pandemics. What is better supported is smaller and stranger: geomagnetic storms can nudge human biology, from sleep to your stress hormones.

So this is a piece about a fascinating maybe, told straight. The connection between solar activity and human health is real in places, oversold in others, and worth understanding either way.

The Solar-Terrestrial Connection

Back in the 1920s, a Russian scientist named Alexander Chizhevsky noticed that life on Earth seemed to keep time with the Sun. He logged stretches of heavy solar activity, measured by sunspots, against the timing of mass events down on Earth, from epidemics to waves of revolution and unrest, and argued the Sun was the conductor.8 Modern reviewers treat him as a pioneer with a strong hunch and uneven evidence. Palmer and colleagues, surveying decades of follow-up work, put a finer point on it: both very high and very low geomagnetic activity track with adverse health effects, and a subset of people seem especially sensitive to those swings.1

The rhythm Chizhevsky was watching has a name now. The Sun runs an 11-year cycle, the Schwabe cycle, swinging from quiet to stormy and back. Near the peak its magnetic field tangles and flips, throwing off more sunspots, solar flares, and the big plasma belches we call solar storms. None of that menaces you directly. Earth’s geomagnetic field takes the hit.

Newer research on solar activity and your health

In 2023, a review in the Taiwan-based journal BioMedicine revisited the whole idea with fresh eyes. Martel and colleagues laid out a plausible pathway: the natural electromagnetic backdrop we evolved inside, including the faint planetary hum called Schumann resonances and the geomagnetic field itself, may help set our circadian rhythm, the internal clock governing sleep, hormones, and mood. Disturb that backdrop, the argument goes, and you may ripple through the body’s daily schedule.2

Notice the verb. May. This is a mechanism that makes sense and has real data behind pieces of it, not a settled law. Most solar-health writing blows right past that distinction.

Do pandemics really track the sunspot cycle?

The pandemic angle is older than you’d guess. In 1990, astronomers Fred Hoyle and Chandra Wickramasinghe published a short note in Nature arguing that influenza pandemics line up with sunspot peaks, and floated the bold idea that solar winds might sweep virus-sized particles down through the upper atmosphere.3 Later studies stretched the claim in both directions, putting pandemics at the extremes of sunspot activity, the very busy years and the very quiet ones alike.4

Then someone checked the math. Epidemiologist Sherry Towers reran the older influenza studies with corrected dates and a more rigorous method, and the pattern came apart. Across every analysis she retested, she found no statistically significant association between sunspot numbers and influenza pandemics, tracing each earlier claim back to data errors or arbitrary cutoffs.4 The boldest spin-off, that solar radiation cranks up microbial mutations and makes pathogens nastier, remains speculation with little behind it.

What about COVID-19? You’ll see it passed around as fresh proof, because the last solar minimum bottomed out in December 2019,7 right when COVID-19’s first cases were surfacing in Wuhan.9 It’s a tidy coincidence. It’s also just one, and nobody has run real statistics on it. Two things are worth remembering before you read anything into it: COVID is a coronavirus, not the influenza those sunspot studies were arguing about, and Towers published in 2017, before the pandemic, so her work never weighed in on it either way.

So where does that leave the link between solar activity and pandemic timing and severity? Unproven, and probably weaker than the charts suggest. Keep an eye on it if it fascinates you, the way you’d track any good unsolved puzzle. Just don’t build a health plan on it yet.

How solar storms reach into your biology

The body’s response to space weather is where the science gets firmer, even if parts of it are still working hypothesis rather than settled fact. Many animals, from insects to migrating birds, read Earth’s geomagnetic field like a compass. One leading explanation involves cryptochrome, a light-sensitive protein in the eye that doubles as a magnetic sensor. When a solar storm rattles the field, researcher James Close has proposed, that compass can misfire and tug on the body’s stress system, the same HPA axis that governs your fight-or-flight hormones.5

There’s a sleep angle too. Studying electric utility workers, Burch and colleagues found that on geomagnetically disturbed nights, people excreted less of a key melatonin byproduct, a hint that storms can quietly trim the sleep hormone.6 Lighter melatonin, a jostled body clock, a nudged stress response: each piece carries some real data, though no single study has strung them into one proven sequence. Modest and plausible, and a long way from the Sun engineering a plague. (If the magnetism-and-life thread grabs you, we go deeper in The Hidden Symphony: How Earth’s Magnetic Field Orchestrates Life.)

Staying informed beats worrying about the Sun

Here’s the empowering part, and the reason staying informed beats worrying. You can’t vote the Sun out of office, but you can watch it. Knowing a strong geomagnetic storm is underway is one more data point for the nights you sleep badly or feel oddly off, the same way you’d glance at a pollen count or a weather forecast before planning your day.

That’s the whole idea behind FlareAware: real-time alerts about solar storms and shifts in solar activity, sized to your curiosity, not your fear. Think of it as a space-weather forecaster in your pocket, useful context rather than a reason to panic.

One thing to be clear about. This article is general information, not medical advice, and the Sun is never a diagnosis. Symptoms deserve the same urgency no matter what space weather is doing. If you or someone near you shows signs of a heart attack or stroke, chest pressure, sudden weakness, trouble speaking or seeing, call emergency services right away.10 (For the cardiovascular side specifically, see Solar Weather and Stroke Risk.)

So how much should public health care about the Sun?

Strip away the hype and a sober shape remains. The surprising link between solar activity and global pandemics is a maybe that the best statistics don’t yet back. The quieter finding, that geomagnetic activity touches human health through sleep, hormones, and the body’s magnetic sense, is on firmer ground and easier to act on. Good public health has always meant reading real signals and ignoring noise, and the Sun gives us both.

Curious where the Sun is in its cycle right now, and whether today’s a stormy one? Sign up for FlareAware’s real-time alerts and follow along. No doom, no dread. Just one more grounded input for taking care of yourself in a world that turns out to be wired to a star 93 million miles away.

References:

  1. Palmer, S.J., Rycroft, M.J. & Cermack, M. (2006). “Solar and geomagnetic activity, extremely low frequency magnetic and electric fields and human health at the Earth’s surface.” Surveys in Geophysics 27(5), 557–595. DOI: 10.1007/s10712-006-9010-7

  2. Martel, J., et al. (2023). “Influence of electromagnetic fields on the circadian rhythm: Implications for human health and disease.” BioMedicine (Taiwan) 13(1). PMC10105029

  3. Hoyle, F. & Wickramasinghe, N.C. (1990). “Sunspots and influenza.” Nature 343, 304. DOI: 10.1038/343304a0

  4. Towers, S. (2017). “Sunspot activity and influenza pandemics: a statistical assessment of the purported association.” Epidemiology & Infection 145(13), 2640–2655. DOI: 10.1017/S095026881700173X (open access)

  5. Close, J. (2012). “Are stress responses to geomagnetic storms mediated by the cryptochrome compass system?” Proceedings of the Royal Society B 279(1736). PMID: 22418257

  6. Burch, J.B., Reif, J.S. & Yost, M.G. (1999). “Geomagnetic disturbances are associated with reduced nocturnal excretion of a melatonin metabolite in humans.” Neuroscience Letters 266(3), 209–212. PMID: 10465710

  7. NASA / NOAA Solar Cycle 25 Prediction Panel (2020). “Solar Cycle 25 Is Here. NASA, NOAA Scientists Explain What That Means.” Solar minimum occurred December 2019. nasa.gov

  8. Chizhevsky, A.L. (1924). Physical Factors of the Historical Process — the founding work of heliobiology, correlating sunspot cycles with epidemics, wars, and waves of social unrest across recorded history. Biographical overview: “Alexander Chizhevsky,” Wikipedia.

  9. U.S. Centers for Disease Control and Prevention, David J. Sencer CDC Museum. “COVID-19 Timeline.” First cluster of pneumonia-like cases reported in Wuhan, China, December 2019. cdc.gov

  10. American Heart Association, “Warning Signs of a Heart Attack” (heart.org); American Stroke Association, “Stroke Symptoms” / B.E. F.A.S.T. (stroke.org).