What is a primary use of infra-red rays in beauty therapy?

Infra-red rays are primarily used in beauty therapy for warming the skin. This is due to their ability to penetrate deep into the tissue, which increases circulation, enhances metabolic processes, and promotes healing. The warmth generated by infra-red rays can help relax muscles, alleviate pain, and enhance the effectiveness of other treatments by increasing blood flow to the area being treated. This warming effect is particularly beneficial in therapies designed to rejuvenate the skin, improve the appearance of cellulite, and aid in the overall relaxation of the body during treatments. In contrast, other options such as cooling the skin, exfoliating, or hydrating are not the primary functions associated with infra-red rays in this context, as these processes involve different approaches and techniques in beauty therapy.