Sleep deprivation negatively impacts appetite and cravings by altering the levels of hormones that regulate hunger, specifically ghrelin and leptin. Ghrelin, which stimulates appetite, increases with lack of sleep, while leptin, which signals satiety, decreases. This imbalance often leads to heightened cravings for unhealthy, high-calorie foods, increasing the risk of weight gain. Furthermore, inadequate sleep can diminish overall energy levels, making individuals less likely to engage in physical activity, thus exacerbating unhealthy eating behaviors.