Red and near-infrared light, too weak to heat tissue, changes how cells produce energy and handle stress. The firmest findings are more hair on a thinning scalp, less pain in arthritic joints and tendons, and fewer mouth ulcers during cancer treatment. Too little light does nothing; too much reverses the benefit. The clearest hazard is to the eyes. (Full Review)
| Marker | Target | Why |
|---|---|---|
| High-sensitivity C-reactive protein (hs-CRP) | < 0.5 mg/L | Systemic inflammatory load; most likely to shift |
| Creatine kinase (CK) | 50–150 U/L (male); 40–120 U/L (female) | Muscle damage; endpoint for recovery protocols |
| Glycated haemoglobin (HbA1c) | 4.8–5.4% | Three-month average blood sugar; metabolic anchor |
| Fasting glucose and fasting insulin | 75–86 mg/dL; < 5 µIU/mL | Detects glucose-handling changes after red light |
| Thyroid-stimulating hormone (TSH) | 0.5–2.0 mIU/L | Baseline thyroid status before neck-directed use |
| Thyroid peroxidase antibodies (TPO-Ab) | < 9 IU/mL | Autoimmune thyroid activity; thyroid-trial endpoint |
| 25-hydroxyvitamin D | 40–60 ng/mL | Skin repair capacity; confounder for skin endpoints |
| Complete blood count with differential | Within conventional range; neutrophil-to-lymphocyte ratio 1.0–2.0 | Screens occult infection that invalidates hs-CRP |
Cadence: Full panel at baseline, 12–16 weeks, then every 6–12 months. Symptom and function tests at 4 weeks; photography at 8 weeks, then every 3 months. Dermatological and retinal examinations annually.