NIR light at 1200 to 1400nm penetrates deeply into the skin and underlying tissues — reaching the dermis-hypodermis junction and superficial muscle layers. The deep warmth: relaxes contracted muscle fibres; stimulates fibroblasts to produce new collagen; causes immediate collagen contraction for mild skin tightening; and improves local microcirculation. The result is a dual therapeutic benefit — muscle relaxation combined with skin firming in a single comfortable session.