Too Little Sleep? Here’s How It Messes with Your Weight and Blood Sugar? ​Getting too little sleep can significantly disrupt your metabolism, leading to weight gain and elevated blood sugar levels. Hormonal Imbalance and Increased Appetite Lack of sleep alters the balance of appetite-regulating hormones:​ Ghrelin: Levels increase, stimulating hunger.​ Leptin: Levels decrease, reducing feelings of fullness.​ This hormonal shift can lead to increased appetite and cravings for high-calorie foods, contributing to weight gain.