How Laser Hair Therapy Works: Photobiomodulation Explained

Laser hair therapy doesn't "zap" hair into growing. It works more like a nudge to cells that are already there but underperforming. The mechanism has a name — photobiomodulation — and it rests on three ideas.

1. Follicles cycle, and pattern hair loss shortens the cycle

Every follicle cycles through a growth phase (anagen, lasting years), a short transition (catagen) and a resting phase (telogen) before the hair sheds and a new one starts. In androgenetic alopecia, follicles become sensitive to DHT, a hormone that gradually shortens the growth phase and shrinks the follicle. Hairs grow shorter, finer and fewer — a process called miniaturisation.

2. Cells absorb red light and make more energy

Red light at roughly 630–680 nm is absorbed by an enzyme in cell mitochondria called cytochrome c oxidase. Researchers believe that absorption increases production of ATP, the cell's energy currency, and triggers signalling changes that reduce inflammation and increase blood flow in the surrounding tissue. ADD CITATION

3. More energy may keep follicles in growth longer

The leading explanation is that better-fuelled follicle cells stay in the anagen phase longer and resting follicles are prompted back into growth. Over months, that shows up as less shedding, then more and thicker hairs. It works only on follicles that still exist, which is why early to moderate thinning responds and long-bald areas don't.

What this means for choosing a device

• Coverage matters. Light only helps the follicles it reaches, so more light sources spread across the scalp means more follicles treated per session — the main reason iRestore leads our ranking.
• Consistency matters. The dose is cumulative. See how long laser therapy takes.
• It's not a cure. Laser therapy manages a chronic condition; stop, and the DHT-driven cycle resumes.

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