Why exactly six weeks between sessions?

Six weeks is the average interval it takes for a new cohort of hairs to cycle from telogen back into anagen on most treatment areas. Facial areas may cycle slightly faster, back and legs slightly slower — your provider tailors the schedule.

Do all hairs on my body cycle at the same rate?

No. Scalp hair has a very long anagen phase (years). Body hair has a much shorter anagen phase (weeks to months), which is why body hair stays shorter and why laser works better on the body than on the scalp.

Does hormonal change affect the cycle?

Yes. Puberty, pregnancy, PCOS, menopause, and certain medications can shift follicles between dormant and active states. This is why occasional maintenance sessions are recommended even after a successful initial series.

Cluster 01 · Basics

Understanding Hair Growth Cycles

Every strand of hair on your body is somewhere in a three-phase cycle. That cycle is why laser hair removal is done as a series rather than a single visit — and why the six-week interval isn't arbitrary.

7 min read Reviewed July 2026

Medically reviewed by Dr. H. Douglas Woodford, MD

Human hair grows in three phases: anagen (active growth), catagen (regression), and telogen (rest). Laser hair removal only works on hairs in the anagen phase, and only 10–30% of the hair in any given area is anagen at once. That's why treatments are spaced roughly six weeks apart — to catch new hairs as they cycle into anagen.

The three phases

Every follicle on your body cycles through these three stages independently:

Phase	What's happening	Duration (body hair)
Anagen	Active growth. The hair is anchored, receiving pigment, and lengthening.	3–6 weeks
Catagen	Transitional. The follicle detaches from its blood supply.	1–2 weeks
Telogen	Resting. The old hair sheds; the follicle prepares for a new cycle.	3–4 months

Why only anagen hairs respond

Anagen is the only phase where the hair shaft is connected to a fully active follicle and loaded with fresh melanin. Melanin is what absorbs the laser light and converts it to heat. A hair in catagen or telogen has less melanin, is loosely attached, and does not efficiently conduct heat to the target we need to disable.

Clinical implication

The laser can only work on the roughly 10–30% of follicles that happen to be in anagen on the day you're treated. Everything else is invisible to it — not because the technology failed, but because there is nothing there to target yet.

How this sets the treatment cadence

The six-week interval used across the Stubble program is calibrated to a simple goal: on each visit, treat a fresh cohort of follicles that have cycled into anagen since the last session. Come back too soon and most follicles haven't returned to anagen yet — you're wasting a session. Come back too late and you miss the window.

Full context on session counts lives in How Many Treatments Will I Need?

Cycles vary by body area

·Facial hair cycles faster — treatment intervals may shorten to 4–5 weeks.
·Underarms and bikini cycle at a moderate pace, ideal for a 6-week rhythm.
·Legs, back, and chest cycle more slowly — sometimes 7–8 weeks.
·Your provider adjusts spacing based on your area, hair density, and how you respond after the first few sessions.

Key takeaways

· Hair cycles through anagen (growth), catagen (regression), and telogen (rest).
· Only anagen hairs contain enough active melanin to respond to the laser.
· 10–30% of hair in any area is in anagen at once — the rest is invisible to the laser.
· The six-week interval is calibrated to catch different hairs on each session.
· Hormonal shifts can activate follicles that were previously dormant, which is why maintenance matters.

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