Skin appearance
How red/NIR light acts on skin: the LLLT mechanism review
Avci, Gupta, Sadasivam, ... Hamblin · 2013 · Seminars in Cutaneous Medicine and Surgery
Avci P, Gupta A, Sadasivam M, Vecchio D, Pam Z, Pam N, Hamblin MR. Low-level laser (light) therapy (LLLT) in skin: stimulating, healing, restoring. Semin Cutan Med Surg. 2013;32(1):41-52.
What they found
The most-cited mechanism review: red/NIR light is absorbed by mitochondrial cytochrome c oxidase, transiently boosting ATP and signaling that can increase fibroblast proliferation, collagen synthesis and angiogenesis. The dose-response is biphasic - too little does nothing and too much can reverse the benefit.
Evidence grade
indirect
Effect direction
positive
Panel relevance
partially replicable
Key outcomes
- Primary photoacceptor is cytochrome c oxidase in mitochondria
- Plausible pathway: more ATP and ROS/NO signaling -> more fibroblast activity and collagen
- Biphasic dose-response: more light is not better
- Explains why red (~600-700 nm) and NIR (~780-900 nm) are the working windows
Protocol details
| Device | Review of lasers and LEDs |
|---|---|
| Wavelengths | 630, 660, 830, 850 nm |
| Irradiance | Not reported |
| Dose (fluence) | Not reported |
| Session time | Not reported |
| Frequency | Not reported |
| Sessions / course | Not reported |
| Study length | Not reported |
| Treatment area | Not reported |
| Study size | Narrative mechanism review (lasers and LEDs in skin) |
Caveats
- This is a mechanism review, not a clinical outcome study - included for context on why and how light may affect skin.
- Mechanistic plausibility does not by itself prove a cosmetic benefit.