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Yes. Stress does give you gray hairs. Here’s how.

It's not just an old superstition — it's your stressed-out brain.

Yes. Stress does give you gray hairs. Here’s how.
Image source: LarsZ/Shutterstock
  • Your brain's fight-or-flight response system is behind the appearance of premature gray hairs.
  • The sympathetic nervous system essentially burns out melanin-producing hair follicles.
  • New research may lead to a greater understanding of the connection between stress and body changes.


It's not your imagination, it turns out. Stress can turn a person's hair gray. It's said that if you look at before and after pictures of any eight-year U.S. president the impact of the office on hair color is clear, though in fairness, it may be that candidates dye their hair and then at some point stop doing so. Nonetheless, scientists from Harvard have not only verified the conventional wisdom on our graying noggins, but have also figured out why stress is so brutal to our follicular pigmentation.

The new research from Harvard scientists is published in the journal Nature.

An unusual chance to see stress at work

Image source: Ververidis Vasilis/Evan El-Amin/Vacclav/Shutterstock/Big Think

Senior author of the study Ya-Chieh Hsu, professor of Stem Cell and Regenerative Biology at Harvard, explains what prompted her research:

"Everyone has an anecdote to share about how stress affects their body, particularly in their skin and hair — the only tissues we can see from the outside. We wanted to understand if this connection is true, and if so, how stress leads to changes in diverse tissues. Hair pigmentation is such an accessible and tractable system to start with — and besides, we were genuinely curious to see if stress indeed leads to hair graying."

It turns out that stress activates nerves associated with our basic fight-or-flight system, and these nerves permanently damage pigment-regenerating melanocyte stem cells in hair follicles, causing them to cease production of melanin that normal provides color to hair follicles.

Hsu's team studied the issue using mice, and was somewhat stunned at their findings. "When we started to study this, I expected that stress was bad for the body — but the detrimental impact of stress that we discovered was beyond what I imagined," recalls Hsu.

The scientists stressed the mice using a combination of three methods:

Who’s in charge here?

Image source: Helga Lei/Shutterstock

Hsu and her colleagues first suspected an immune system reaction was at the root of graying hairs only to discover that mice without immune systems still turned gray in response to stressors. The next suspect was cortisol produced by the adrenal glands — however, this proved not to be so. "Stress always elevates levels of the hormone cortisol in the body," says Jsu, "so we thought that cortisol might play a role. But surprisingly, when we removed the adrenal gland from the mice so that they couldn't produce cortisol-like hormones, their hair still turned gray under stress."

It’s the sympathetic nervous system

Image source: Judy Blomquist/Harvard University

Finally, the researchers investigate the possibility that the system responding to stressors was the mice's sympathetic nervous systems, the part of the nervous system that kicks into action with the fight-or-flight impulse. The sympathetic nervous system is a vast network of nerves that connects, among other places, to hair follicles in the skin. In response to stress, the system sends a rush of the chemical norepinephrine to the follicles' melanocyte stem cell, causing them to quickly burn through and deplete their stores of pigment.

Say Hsu, "After just a few days, all of the pigment-regenerating stem cells were lost. Once they're gone, you can't regenerate pigments anymore. The damage is permanent." Great for survival, not so good for hair color.

A big hint of a much greater insight

Sympathetic system nerves are magenta above. Melanocyte stem cells are yellow.

Image source: Hsu Laboratory, Harvard University

"Acute stress," says lead author of the study Bing Zhang, "particularly the fight-or-flight response, has been traditionally viewed to be beneficial for an animal's survival. But in this case, acute stress causes permanent depletion of stem cells."

The research, done in collaboration with other Harvard researchers, presents a new appreciation of the effect the sympathetic system can have on the body's cells during stress.

One of these collaborators, Harvard immunologist Isaac Chu, notes, "We know that peripheral neurons powerfully regulate organ function, blood vessels, and immunity, but less is known about how they regulate stem cells. With this study, we now know that neurons can control stem cells and their function, and can explain how they interact at the cellular and molecular levels to link stress with hair graying."

Given this finding regarding the direct impact of stress on follicular stem cells, the question of what it else it may affect becomes an obvious one. As Hsu sums it up, "By understanding precisely how stress affects stem cells that regenerate pigment, we've laid the groundwork for understanding how stress affects other tissues and organs in the body."

This importance of the study therefore goes way beyond graying heads. "Understanding how our tissues change under stress is the first critical step," says Hsu, "toward eventual treatment that can halt or revert the detrimental impact of stress. We still have a lot to learn in this area."

Radical innovation: Unlocking the future of human invention

Ready to see the future? Nanotronics CEO Matthew Putman talks innovation and the solutions that are right under our noses.

Big Think LIVE

Innovation in manufacturing has crawled since the 1950s. That's about to speed up.

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Your body’s full of stuff you no longer need. Here's a list.

Evolution doesn't clean up after itself very well.

Image source: Ernst Haeckel
Surprising Science
  • An evolutionary biologist got people swapping ideas about our lingering vestigia.
  • Basically, this is the stuff that served some evolutionary purpose at some point, but now is kind of, well, extra.
  • Here are the six traits that inaugurated the fun.
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Quantum particles timed as they tunnel through a solid

A clever new study definitively measures how long it takes for quantum particles to pass through a barrier.

Image source: carlos castilla/Shutterstock
  • Quantum particles can tunnel through seemingly impassable barriers, popping up on the other side.
  • Quantum tunneling is not a new discovery, but there's a lot that's unknown about it.
  • By super-cooling rubidium particles, researchers use their spinning as a magnetic timer.

When it comes to weird behavior, there's nothing quite like the quantum world. On top of that world-class head scratcher entanglement, there's also quantum tunneling — the mysterious process in which particles somehow find their way through what should be impenetrable barriers.

Exactly why or even how quantum tunneling happens is unknown: Do particles just pop over to the other side instantaneously in the same way entangled particles interact? Or do they progressively tunnel through? Previous research has been conflicting.

That quantum tunneling occurs has not been a matter of debate since it was discovered in the 1920s. When IBM famously wrote their name on a nickel substrate using 35 xenon atoms, they used a scanning tunneling microscope to see what they were doing. And tunnel diodes are fast-switching semiconductors that derive their negative resistance from quantum tunneling.

Nonetheless, "Quantum tunneling is one of the most puzzling of quantum phenomena," says Aephraim Steinberg of the Quantum Information Science Program at Canadian Institute for Advanced Research in Toronto to Live Science. Speaking with Scientific American he explains, "It's as though the particle dug a tunnel under the hill and appeared on the other."

Steinberg is a co-author of a study just published in the journal Nature that presents a series of clever experiments that allowed researchers to measure the amount of time it takes tunneling particles to find their way through a barrier. "And it is fantastic that we're now able to actually study it in this way."

Frozen rubidium atoms

Image source: Viktoriia Debopre/Shutterstock/Big Think

One of the difficulties in ascertaining the time it takes for tunneling to occur is knowing precisely when it's begun and when it's finished. The authors of the new study solved this by devising a system based on particles' precession.

Subatomic particles all have magnetic qualities, and they spin, or "precess," like a top when they encounter an external magnetic field. With this in mind, the authors of the study decided to construct a barrier with a magnetic field, causing any particles passing through it to precess as they did so. They wouldn't precess before entering the field or after, so by observing and timing the duration of the particles' precession, the researchers could definitively identify the length of time it took them to tunnel through the barrier.

To construct their barrier, the scientists cooled about 8,000 rubidium atoms to a billionth of a degree above absolute zero. In this state, they form a Bose-Einstein condensate, AKA the fifth-known form of matter. When in this state, atoms slow down and can be clumped together rather than flying around independently at high speeds. (We've written before about a Bose-Einstein experiment in space.)

Using a laser, the researchers pusehd about 2,000 rubidium atoms together in a barrier about 1.3 micrometers thick, endowing it with a pseudo-magnetic field. Compared to a single rubidium atom, this is a very thick wall, comparable to a half a mile deep if you yourself were a foot thick.

With the wall prepared, a second laser nudged individual rubidium atoms toward it. Most of the atoms simply bounced off the barrier, but about 3% of them went right through as hoped. Precise measurement of their precession produced the result: It took them 0.61 milliseconds to get through.

Reactions to the study

Scientists not involved in the research find its results compelling.

"This is a beautiful experiment," according to Igor Litvinyuk of Griffith University in Australia. "Just to do it is a heroic effort." Drew Alton of Augustana University, in South Dakota tells Live Science, "The experiment is a breathtaking technical achievement."

What makes the researchers' results so exceptional is their unambiguity. Says Chad Orzel at Union College in New York, "Their experiment is ingeniously constructed to make it difficult to interpret as anything other than what they say." He calls the research, "one of the best examples you'll see of a thought experiment made real." Litvinyuk agrees: "I see no holes in this."

As for the researchers themselves, enhancements to their experimental apparatus are underway to help them learn more. "We're working on a new measurement where we make the barrier thicker," Steinberg said. In addition, there's also the interesting question of whether or not that 0.61-millisecond trip occurs at a steady rate: "It will be very interesting to see if the atoms' speed is constant or not."

Self-driving cars to race for $1.5 million at Indianapolis Motor Speedway ​

So far, 30 student teams have entered the Indy Autonomous Challenge, scheduled for October 2021.

Illustration of cockpit of a self-driving car

Indy Autonomous Challenge
Technology & Innovation
  • The Indy Autonomous Challenge will task student teams with developing self-driving software for race cars.
  • The competition requires cars to complete 20 laps within 25 minutes, meaning cars would need to average about 110 mph.
  • The organizers say they hope to advance the field of driverless cars and "inspire the next generation of STEM talent."
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Mind & Brain

The dangers of the chemical imbalance theory of depression

A new Harvard study finds that the language you use affects patient outcome.

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