Red light therapy (630–700nm) penetrates the dermis, stimulating fibroblasts and ATP production to boost collagen, elasticity, and skin tone—making it effective for anti-aging. Blue light (~415nm) stays surface-level, targeting acne bacteria, not wrinkles. For anti-aging, choose dual-wavelength 660nm/850nm devices, used 3–5 times weekly for 8–12 weeks.