Why Hair Turns Grey — The System, Mapped

The Language of the Follicle: How Cell Signalling Shapes Greying

Hair keeps its colour through coordination. This episode explores the signalling language of the hair follicle and what changes when that coordination begins to break down. We look at why the relationship between the niche and the bulb matters, how endothelin and EDNRB signalling help maintain the pigment system, and what happens when these signals become weak or noisy. Watch our previous episodes on the six drivers of hair ageing, reversibility, and the mechanism by which stress greys hair to see the full picture.

Saving Pigment Stem Cells — Luteolin in a Greying Model

Grey hair was long treated as the territory of myths — but today we’re moving toward molecular solutions. This episode explores Luteolin, a plant flavonoid being tested as an agent to protect the hair’s pigment system. We break down findings from a Nagoya University study, where researchers were able to track how antioxidants affect the hair follicle. The key focus is protecting the “bank” of stem cells in the follicle bulge. Luteolin helps the system cope with oxidative stress before damage becomes irreversible, slowing the loss of colour. This is another piece of our broader map of greying. Watch the previous episodes on the six drivers of hair ageing and the impact of stress to see the full picture.

How Stress Greys — The Mechanism

People have long suspected that stress turns hair grey. We finally have the map of how it happens. For a long time, stories of sudden greying—from Marie Antoinette to modern presidencies—were seen as folklore. But recent studies have traced the direct, hardwired pathway linking the brain’s survival response to the hair follicle. This video breaks down that mechanism. It explains how the sympathetic nervous system, designed for "fight or flight," bypasses slower hormonal routes to deliver a shock of noradrenaline directly to the stem cell niche. We visualize how this signal triggers a "bank run" on pigment-producing cells—forcing them to activate and deplete all at once, leaving the follicle without a reserve for the future. This mechanism is just one part of the biological landscape we are exploring. In our previous episodes, we mapped the six main drivers of greying and analyzed the study proving that—within a specific window—this process can be reversed. Watch those to see the full picture, and subscribe to follow the science of hair health.

Is Hair Greying Reversible? — What a Single Hair Strand Reveals

Hair greying is usually treated as one-way: once a follicle stops producing pigment, colour is assumed to be gone for good.But a study from Columbia University introduced a way to test that assumption — by treating individual hair strands as approximate biological timelines. Because scalp hair grows at a relatively consistent rate, different segments along a single strand correspond to different periods in the recent past. By analysing pigmentation along the length of individual hairs, the researchers reconstructed how pigment output changed over time. Some follicles followed the expected path: dark hair transitioning to grey, with no return. Others showed a different pattern — a grey segment followed by a darker one on the same strand.This does not mean the hair fibre recoloured. Instead, it indicates that the follicle temporarily lost pigment production and later restarted it while the hair was still growing. These findings suggest that greying can behave as a dynamic process, influenced by cumulative biological and psychological stress, rather than a strictly irreversible failure. In some follicles — at least for a limited period — pigment production can restart.

Why Hair Turns Grey — The System, Mapped

Greying doesn’t happen at a single point. It unfolds across a biological system. In this episode, we lay out the main routes that shape how hair gradually loses colour — from the cells that supply pigment, to the signals that guide them, and the biochemical and structural conditions that determine whether colour holds. Together, these drivers form a system-level map of greying and help explain why the process unfolds the way it does.