A hair can shed while its follicle stays put
The strand you see is dead, keratinized material; the living machinery is the follicle beneath the skin. A follicle repeatedly shifts through a long growth phase, a brief transition, and a resting phase. At the end of rest, the old strand is released, and the follicle can begin growing another.
These phases do not take the same amount of time in every follicle. Scalp hairs spend much longer growing than resting, but each follicle starts and ends those phases on its own timetable. That staggered timing is why shedding is spread across the day rather than concentrated into one dramatic event.
What keeps the shedding gradual
If many follicles paused growth together, they could reach the shedding stage together, too. Instead, neighboring follicles are usually at different points in their cycles. So while some release their old strands, others are still growing hair or holding onto strands in the resting phase. The scalp continually replaces hair without needing every follicle to coordinate with the rest.
A change in the body can sometimes shift more follicles than usual into a resting phase. Because shedding comes later, the effect may not be immediate: an increase in loose hairs can become noticeable after a delay. Even then, it is typically a larger wave of shedding, not every follicle emptying at once. The key is that hair loss is paced by individual follicles, not by the scalp as a single unit.
