Red light therapy—aka photobiomodulation (PBM)—uses non-heating red/near-infrared light to nudge cellular signaling, likely via mitochondrial enzymes such as cytochrome-c oxidase. What does that mean for you? In this 10-minute quickcast, Chris separates solid clinical uses from hype. PBM is recommended in oncology guidelines for preventing/treating oral mucositis (painful mouth sores from chemo/radiation). It also has FDA-cleared devices for pattern hair loss, with trials showing increased hair counts when used consistently. In dermatology, trials suggest modest improvements in fine lines/texture and adjunct benefits in acne; and for some musculoskeletal pains (e.g., tendinopathy), meta-analyses show small-to-moderate benefits when dosing is correct—best as an adjunct to rehab. Evidence is mixed for exercise performance/recovery and thin for broad “longevity” or fat-loss claims. PBM is generally safe when used properly, but overuse can cause burns, and eye exposure deserves caution; dosing and indication matter. If you try it, pick a reputable device (for hair, look for FDA 510(k) clearance), follow manufacturer parameters (typical red/near-IR wavelengths), start with short sessions 2–4×/week, and re-evaluate after 8–12 weeks. Adjunct, not miracle.