The Hair Growth Cycle Explained — And How Red Light Therapy Works With It
What’s Really Happening Beneath Your Scalp — and Why It Matters for Treating Hair Loss
If you’ve ever started a hair loss treatment and wondered, “Why isn’t this working yet?” — you’re not alone. It’s one of the most common frustrations people face, and it usually comes down to one thing: a misunderstanding of how hair actually grows – the hair growth cycle.
Hair doesn’t grow continuously like grass. It follows a precise biological cycle — one that unfolds over months and years, not days and weeks. Once you understand that cycle, the timeline for seeing results from treatments like red light therapy, minoxidil, or supplements starts to make a lot more sense. And more importantly, you’ll understand why sticking with your regimen is the single most important thing you can do.
The Four Phases of Hair Growth
Every hair on your head is on its own independent journey through a repeating cycle. At any given moment, some hairs are actively growing, some are winding down, some are resting, and some are falling out to make room for new ones. This is completely normal — in fact, most people shed between 50 and 100 hairs per day without noticing any thinning at all.
The hair growth cycle breaks down into four distinct phases:
1. Anagen — The Active Growth Phase
This is where the magic happens. During the anagen phase, the hair follicle is fully active. Cells in the hair bulb divide rapidly, pushing the hair shaft upward and out through the scalp. On a healthy head, roughly 85 to 90 percent of all hairs are in this phase at any given time.
Anagen typically lasts between two and seven years, depending on your genetics, age, health, and hormonal balance. The length of your anagen phase is what determines how long your hair can grow before it naturally stops. As we age, the anagen phase tends to shorten, which is one reason hair may become thinner and grow more slowly over time.
2. Catagen — The Transition Phase
Once a hair finishes its growth period, it enters catagen — a brief transitional phase lasting about two to three weeks. During this stage, the hair follicle shrinks and detaches from the blood supply that was fueling it. Growth slows to a halt, and the lower part of the follicle begins to break down.
Only about one to three percent of your hair is in catagen at any time. Think of it as the follicle’s way of powering down before a rest period.
3. Telogen — The Resting Phase
Telogen is the quiet phase. The old hair sits in place while the follicle rests, typically for two to three months. About nine to fifteen percent of your scalp hair is in this phase at any given time. The hair isn’t growing, but it isn’t falling out yet either — it’s simply waiting.
In people experiencing hair loss, a disproportionately high number of follicles can get stuck in the telogen phase. This condition, known as telogen effluvium, is often triggered by stress, illness, hormonal changes, nutritional deficiencies, or medication. The result is noticeable shedding and thinning.
4. Exogen — The Shedding Phase
Exogen is sometimes considered an extension of telogen. This is when the resting hair finally releases from the follicle and falls out. At the same time, a new hair begins forming beneath the surface, preparing to start the cycle all over again in the anagen phase.
This is the shedding you see in your brush, in the shower drain, or on your pillow. It’s a natural and necessary part of healthy hair turnover.
What Goes Wrong When You’re Losing Hair
In a healthy hair cycle, the balance between phases stays relatively stable. But when something disrupts that balance — whether it’s genetics, hormones, stress, poor nutrition, or aging — the cycle shifts in a problematic direction.
The most common pattern in both male and female hair loss (androgenetic alopecia) is a shortening of the anagen phase and a lengthening of the telogen phase. Fewer follicles are actively growing at any given time, and the ones that are growing produce thinner, weaker hairs. Over time, some follicles miniaturize to the point where they stop producing visible hair altogether.
This is why effective hair loss treatment isn’t just about stopping shedding — it’s about restoring the balance of the cycle. And that’s exactly where red light therapy comes in.
How Red Light Therapy (LLLT) Works With Your Hair’s Natural Cycle
Low-level light therapy (LLLT) — the technology behind the GroWell Red Light Therapy Cap — works by delivering specific wavelengths of red and near-infrared light directly to the scalp. This light penetrates the skin and is absorbed by the mitochondria inside your cells, triggering a process called photobiomodulation.
In practical terms, here’s what that means for your hair cycle:
It stimulates follicles to re-enter the anagen (growth) phase. Research has shown that LLLT can encourage dormant, resting follicles to shift from the telogen phase back into active growth. This is one of the most important mechanisms for reversing thinning — waking up follicles that have gone quiet.
It prolongs the anagen phase. Red light therapy doesn’t just restart growth — it helps hair stay in the growth phase longer, giving each strand more time to develop fully before transitioning to catagen. Longer anagen means thicker, stronger, and more resilient hair.
It boosts cellular energy and blood flow. By increasing ATP (adenosine triphosphate) production in follicle cells, LLLT gives your hair the energy it needs to grow. It also promotes vasodilation — improved blood circulation to the scalp — which enhances the delivery of oxygen and nutrients to each follicle.
It reduces inflammation. Chronic low-grade inflammation around hair follicles is a contributing factor in many types of hair loss. Red light therapy has been shown to help reduce oxidative stress and calm inflammation, creating a healthier environment for hair to grow.
This is why dermatologists and hair transplant surgeons recommend red light therapy as both a standalone treatment and a complement to other approaches like minoxidil, finasteride, PRP, and hair transplant surgery.
Why the GroWell Cap Is Built for the Hair Growth Cycle
Understanding the hair growth cycle makes one thing crystal clear: results take time. Your follicles need to transition through biological phases that unfold over weeks and months, not days. That’s why consistency is everything.
The GroWell Red Light Therapy Cap was designed with this reality in mind. Developed by Apira Science, with more than 20 years of expertise in medical-grade LLLT, the GroWell cap is FDA-cleared and was proven 100% effective in two double-blind, placebo-controlled clinical studies. But what truly sets it apart is its design for everyday life.
Unlike bulky laser helmets or rigid inserts, the GroWell’s modular light panel can be removed from the included cap and placed inside most of your own hats. That means you can do a treatment while working at your desk, running errands, or relaxing at home — without anyone knowing. When a treatment is easy to do, you’re far more likely to stay consistent. And consistency is what moves your follicles from resting back to growing.
What to Expect: A Red Light Therapy Timeline for Hair Regrowth
Now that you understand the hair growth cycle, here’s a general timeline for what to expect when using a red light therapy cap like the GroWell:
Month 1–2: You may not see visible changes yet, and that’s completely normal. Your follicles are beginning to respond at a cellular level — increased blood flow, improved energy production, and early shifts from telogen toward anagen. Some users notice reduced shedding during this period.
Month 3–4: This is typically when the first visible signs of progress appear. Many users report that their hair feels thicker and stronger, and areas of thinning may start to fill in. Hair that was miniaturizing may begin producing thicker strands.
Month 5–6 and beyond: With consistent use, continued improvement in hair density, coverage, and overall hair quality is expected. Clinical studies on LLLT devices have demonstrated significant increases in hair count and thickness at the four- to six-month mark.
The key word throughout this timeline is consistent. Your hair cycle doesn’t pause for skipped sessions. The more regularly you use your GroWell cap, the more effectively you’re supporting each follicle’s journey back into active growth.
Accelerate Your Results With a Complete Regimen
Red light therapy is powerful on its own, but it’s even more effective when combined with complementary treatments that support your hair cycle from multiple angles. GroWell offers a full ecosystem of hair health products designed to work together:
GroWell Repair & Restore Shampoo and Conditioner — formulated to cleanse and nourish the scalp, creating an optimal environment for healthy follicle function.
GroWell Hair Health Supplements for Women and Men — packed with biotin, marine collagen, saw palmetto, and essential vitamins to feed your follicles from the inside out.
GroWell Topical Minoxidil for Women and Men — a clinically proven topical that works synergistically with red light therapy to promote regrowth.
For the best value, the GroWell All-In Hair Growth Bundle combines the red light cap with a four-month supply of shampoo, conditioner, supplements, and topical treatment — everything you need to address hair loss from every angle.
Frequently Asked Questions
How long does it take for red light therapy to work on hair loss? Most users begin to notice reduced shedding around weeks 8–12, with visible density improvements typically appearing at the four- to six-month mark. Hair regrowth follows your biological cycle, so patience and consistency are essential.
How often should I use a red light therapy cap? Most clinical protocols recommend 2–4 sessions per week, each lasting 10–20 minutes. Following the GroWell cap’s recommended schedule gives your follicles the regular stimulation they need without overdoing it.
Can I use red light therapy alongside minoxidil or finasteride? Yes LLLT is well-established as a complementary treatment alongside minoxidil and finasteride. The approaches target different mechanisms, so combining them tends to outperform monotherapy. Apply minoxidil after your red light session, not before.
Does red light therapy work for women as well as men? Yes. Both men and women with androgenetic alopecia and telogen effluvium have shown improvements in clinical studies. Women often see fuller coverage across the crown, while men tend to notice regrowth around the hairline and crown.
Trust the Process
Hair loss can feel urgent, but hair regrowth is a gradual, biological process. Understanding the growth cycle is the first step toward setting realistic expectations — and making smarter decisions about treatment.
The GroWell Red Light Therapy Cap works with your body’s natural cycle, not against it. It helps dormant follicles wake up, keeps growing hairs in the growth phase longer, and supports the cellular energy your hair needs to thrive. It’s drug-free, FDA-cleared, clinically proven, and designed to fit seamlessly into your daily routine.
The best time to start treating hair loss is before it progresses further. And the best way to see results is to stay the course.
Frequently Asked Questions About Hair Growth Cycles and Red Light Therapy for Hair Regrowth
What are the four phases of the hair growth cycle?
Every hair on your head moves independently through four phases: anagen (active growth), catagen (a brief transition), telogen (resting), and exogen (shedding). At any moment, different hairs are in different phases, which is why you’re always shedding some hairs while others keep growing.
What is the anagen phase?
Anagen is the active growth phase, where cells in the hair bulb divide rapidly and push the hair shaft up through the scalp. It lasts anywhere from two to seven years depending on genetics, age, health, and hormones. Roughly 85–90% of the hairs on a healthy scalp are in anagen at any given time. The length of your anagen phase is what determines how long your hair can grow before it naturally stops.
What is the catagen phase?
Catagen is a short transitional phase lasting about two to three weeks. The follicle shrinks, detaches from its blood supply, and growth stops. Only 1–3% of your hair is in catagen at any time — think of it as the follicle powering down before a rest period.
What is the telogen phase?
Telogen is the resting phase, lasting two to three months. The hair sits in place — not growing, not falling out — while the follicle takes a break. About 9–15% of scalp hair is in telogen at any time. When too many follicles get stuck here (a condition called telogen effluvium), the result is noticeable shedding and thinning. Common triggers include stress, illness, hormonal changes, nutritional deficiencies, and certain medications.
What is the exogen phase?
Exogen is the shedding phase, sometimes considered an extension of telogen. The old, resting hair finally releases from the follicle and falls out — this is what you see in your brush, the shower drain, or on your pillow. At the same time, a new hair is already forming underneath to restart the cycle in anagen.
What goes wrong with the hair cycle when you're losing hair?
The most common pattern in male and female pattern hair loss (androgenetic alopecia) is a shortened anagen phase and a lengthened telogen phase. Fewer follicles are actively growing, and the ones that are produce thinner, weaker hairs. Over time, some follicles miniaturize so much that they stop producing visible hair at all. Effective treatment isn’t just about stopping shedding — it’s about restoring balance to the cycle.
How does red light therapy interact with the hair growth cycle?
It works with the cycle in four ways: it nudges dormant follicles out of telogen and back into anagen, prolongs the anagen phase so each hair grows longer and thicker before transitioning, boosts cellular energy (ATP) and blood flow to support active growth, and reduces inflammation that can keep follicles stuck in unproductive phases.
Why does hair seem to grow more slowly as I get older?
The anagen (growth) phase tends to shorten with age, so hairs spend less time actively growing before transitioning out. This is one reason hair often becomes thinner and grows more slowly over time, even in people without pattern hair loss.