Every hair on a man's head is running on a repeating biological timetable, and most of the habits that shape hair health — from what's on his plate to how often he washes his scalp — act on that timetable in specific, identifiable ways. Hair grows through three main phases: anagen (active growth), catagen (transition), and telogen (rest), followed by shedding. Thinning in men usually reflects disruption inside that cycle — a genetically driven shortening of it — rather than hair simply "falling out" at random. Understanding which phase a problem strikes tells a man where his routine can actually help.
Understanding the Male Hair Growth Cycle
The scalp is covered with roughly 100,000 to 150,000 hairs, and each individual follicle moves through its own cycle independent of its neighbors, according to Regaine's explanation of the growth process. Because the follicles are out of sync with one another, a healthy head loses hair continuously — up to about 100 hairs a day — without any visible change in density. That daily shedding is the cycle's normal exit step, not a warning sign. Trouble begins only when follicles are pushed to cycle faster or rest longer than they should, which reduces the number and thickness of hairs growing at any moment.
Anagen: The Active Growth Phase
Anagen is the engine of the cycle. Cells at the root of the follicle divide rapidly, building the hair shaft strand by strand. Hair grows around half an inch per month — roughly six inches per year — and often faster in summer, as trichologist Anabel Kingsley of the Philip Kingsley clinic explains. The longer a follicle stays in anagen, the longer and thicker the resulting hair can become. That makes anagen the most consequential phase for a man worried about density: anything that shortens it produces shorter, finer hairs over successive cycles, and anything that keeps follicles in it longer preserves coverage.
Catagen and Telogen: Transition and Rest
After anagen, each follicle passes through a brief transitional stage and then into telogen, the resting phase, where the old hair sits in place while the follicle below it lies dormant. Shedding follows — some sources describe this as a fourth stage, exogen, though the men's health platform Manual notes this is better understood as the moment the telogen hair gives way to a new anagen hair rather than a truly separate phase. Telogen matters to men for two reasons. First, it's when shed hairs become visible in the drain or on the pillow. Second, several disruptions — stress, illness, nutritional deficiency — can push large numbers of follicles into telogen prematurely, producing a diffuse, noticeable wave of shedding a few months after the trigger.
