Kenogen
The empty-follicle phase nobody warns you about. Your scalp's awkward gap year between hairs.
Grounded in the research on Human hair growth (Wikipedia) — hair follicle cycle: anagen, catagen, telogen, exogen, kenogen
What kenogen actually is
Kenogen is the phase where a hair follicle sits EMPTY. Old hair already shed, new hair not growing yet. Just an idle pore. Most people think the hair cycle is anagen (grow) to catagen (transition) to telogen (rest) to exogen (shed), then straight back to growing. It is not. There is a dead-air gap between shed and regrow, and that gap is kenogen. The word is Greek: 'keno' = empty. It is a normal phase, not damage.
Who named it and why it matters
Coined around 2002 by Italian dermatologists Alfredo Rebora and Marcello Guarnieri. Before them, the empty-follicle window was invisible in the textbook cycle, so hair counts and shedding math were off. Naming kenogen mattered because it explained why scalp density can drop even when total follicle count is unchanged: follicles can be alive but vacant. You are not always losing follicles. Sometimes they are just between tenants.