Sleep deprivation negatively impacts metabolic rate by disrupting the body's hormonal balance. Lack of sleep leads to an increase in ghrelin, the hormone that stimulates appetite, and a decrease in leptin, which signals satiety. This imbalance not only promotes increased hunger but also affects the body’s ability to burn calories effectively. Furthermore, sleep deprivation can lead to reduced insulin sensitivity, resulting in higher blood sugar levels and an increased risk of weight gain and related health issues.