In 2023, Daniel P. Windred and a team studied sleep patterns in thousands of adults across multiple cohorts, finding that sleeping in on weekends, called social jetlag, disrupts your body’s internal clock. Each hour of jetlag raises heart disease risk by 11% and worsens mood, obesity, and unhealthy habits like smoking or poor diet. A 2019 study by C.M. Depner showed that catching up on sleep after five short nights still caused 10-15% worse insulin sensitivity and higher calorie intake, leading to weight gain risks.