The hypothesis that leptin deficiency is related to apnea has been proposed based on the finding that leptin acts as an appetite suppressant and ventilatory stimulant in rats, as well as the strong association between obesity and OSAS in humans. Recent studies related to metabolic syndrome have shown that individuals with OSAS have higher levels of leptin, indicating the presence of relative leptin resistance and insulin resistance [8]. Here, LEP is linked to obesity due to melanocortin 4 receptor deficiency.