Low-level light therapy (LLLT) with LEDs is the therapeutic use of incident light to photomodulate cellular function to improve and quicken wound healing, treat acne, rejuvenate the appearance of skin, stimulate hair growth, improve local circulation, perform 5-ALA photodynamic therapy (PDT), and relieve pain and stiffness in muscles and joints. Cells absorb light energy without incidence of damage from heat or physical trauma; various cellular functions are upregulated enhancing cell repair and function as well as stimulating proliferation.