ISS astronauts return with gray hair — here’s what’s behind the shocking color shift

NY Post ^ | March 20, 2025, | Brooke Kato

[BenLurkin]

While there are no scientific studies that link spaceflight to graying hair, NASA has previously suggested that spending time in space can cause “significant physiological changes.”

“Imagine if all of your physiological changes were hyper-accelerated so that you passed through life cycles in weeks as opposed to decades,” NASA wrote online when the agency announced it would be launching a “space-age” research program to study space’s effects on the human body.

“You’d be able to grow a beard overnight or your hair might begin graying in a matter of days or maybe menopause would come knocking by next weekend.”

NASA continued: “This may seem like a far stretch from reality, but spaceflight causes significant physiological changes including an accelerated loss of muscle and bone density, and immune system dysfunction that parallel the effects of natural aging here on Earth.”

In fact, a 2016 study “found that spaceflight alters human hair follicle gene expression,” reporting that, in some astronauts, the genes responsible for regulating hair growth were “upregulated,” meaning the genes could inhibit “cell proliferation” within the hair follicles.

While men appeared to disproportionately experience the phenomenon compared to women, the researchers suggested that, based on their findings, spaceflight could potentially result in hair loss.

Some observers at home have a simpler explanation for WIlliams’ silver tresses: a lack of hair dye aboard the ISS.

“A few have asked me why Sunita Williams has grey hair and looks ‘tired’ coming back home from space,” Emily Carney, a former US Navy nuclear technician and space historian, wrote on Threads.

“This is because in space there’s no hair dye or makeup mirror at your disposal.”

[Rio]

She’s 59 years old. Grey is likely I should think. Would not have shown during the original short-duration mission.

[metmom]

“A few have asked me why Sunita Williams has grey hair and looks ‘tired’ coming back home from space,” Emily Carney, a former US Navy nuclear technician and space historian, wrote on Threads.

Nine months of being confined to that small a space and they have to ask?????????

[FoxInSocks]

You could have searched for “Admiral Ackbar” instead of “Star Wars fish guy.”

[brooklin]

I think you have hit on the correct answer.

[Pennsyltucky Boy]

Apparently no scrunchies or hair bans either. That may be what comes of allowing your hair to stand on end for 8 or 9 months. Can you imagine the amount of loose hair drifting around in that space station?

[Governor Dinwiddie]

The irony is that the workers who assemble this stuff work in clean rooms which automatically
vacuum you upon entry. They require hair covering and clean room overalls and shoes.