INS and mood disorder: Numerous studies have shown that swimming in cold water can bring many health benefits [21], including lowering blood pressure [22,23,24,25,26], hormonal balance [27,28,29], increased tissue sensitivity to insulin [21,27,30], reduced frequency and a milder course of upper respiratory tract infections [31,32,33], favorable effects on lipid metabolism [23,27,34,35], improvement of hematological parameters [36,37], stimulation of the immune system [38,39,40], alleviation of mood disorders [41], and the improvement of general well-being [42].