Sunita Williams returns with gray hair—Extended ISS stay to blame?
What's the story
NASA astronauts Barry Wilmore and Sunita Williams recently returned from a nine-month-long mission aboard the International Space Station (ISS).
Their homecoming, however, was marred by an unexpected surprise: Williams's hair had turned gray.
This change led to speculation about the effect of prolonged exposure to zero gravity on human physiology.
Despite no scientific evidence linking space travel to graying hair, NASA has acknowledged that extended periods in space can induce significant physiological changes.
Space program
NASA's research program on space's impact on human body
NASA has proposed a "space-age" research initiative to explore how space travel affects the human body.
The agency described this project as studying "significant physiological changes."
It further explained that these changes could be an accelerated aging process, where life cycles are condensed into weeks instead of decades.
This could lead to rapid beard growth, premature hair graying, or even early onset of menopause.
Gene alteration
Space travel's impact on hair follicle gene expression
A 2016 study found that space travel alters human hair follicle gene expression. In some astronauts, genes regulating hair growth were "upregulated," potentially inhibiting "cell proliferation" within the follicles.
This phenomenon appeared more common in men than women.
Another 2015 study revealed that mice exposed to three months of space conditions experienced changes like thinner skin and disrupted hair follicle cycles.
Stress impact
Oxidative stress and its potential role in hair graying
Previous research has indicated a connection between space travel and heightened oxidative stress, a condition that experts believe leads to aging and subsequently hair graying.
However, no study has directly linked oxidative stress from space travel to changes in hair color.
Some speculate that Williams's gray hair could simply be due to lack of access to hair dye on the ISS.
Recovery phase
Astronauts' recovery and reconditioning post-space mission
Wilmore and Williams spent 286 days on the ISS after Boeing's Starliner spacecraft malfunctioned, prolonging their mission beyond its planned duration of just over a week.
After returning to Earth, the astronauts are undergoing a long recovery process to readjust to gravity.
They are going through a 45-day reconditioning program involving rigorous physical therapy.