The results of a new study have revealed a complex relationship between sleep duration and metabolism. The analysis showed that the lowest risk of developing insulin resistance—a condition that often precedes type 2 diabetes—was observed in people who slept exactly 7 hours and 18 minutes per night. Any deviation from this duration, whether shorter or longer sleep, was associated with an increased risk of metabolic disorders.

Previous experimental data had already indicated the importance of sleep for glucose metabolism. Even a few days of insufficient sleep can reduce tissue sensitivity to insulin—the hormone that regulates blood sugar levels. As a result, glucose is absorbed less efficiently by cells, leading to its accumulation in the bloodstream.

Insulin resistance can lead to the development of type 2 diabetes and other metabolic disorders. Many people try to make up for lack of sleep during the workweek by sleeping longer on weekends.

The study, conducted by specialists from Nantong University (China), was based on data from the National Health and Nutrition Examination Survey, which took place in the United States from 2009 to 2023. Nearly 23,500 people aged 20 to 80 participated in the analysis, with about 11,000 reporting their sleep duration on both weekdays and weekends.

The results showed that the relationship between sleep duration and the rate of glucose utilization forms an inverted U-shaped curve, with the optimal value at 7 hours and 18 minutes. Both shorter and longer sleep were linked to a decrease in glucose utilization rate and, consequently, an increased risk of insulin resistance. This effect was especially pronounced in women and in both men and women aged 40 to 59.

Additional sleep on weekends proved beneficial for those who regularly lacked sleep during the week, improving their metabolic indicators. However, for those who already slept too long on weekdays, increasing sleep duration on weekends led to a deterioration in metabolic health.

The study confirms the existence of a complex, two-way relationship between sleep and metabolism. Metabolic disorders increase the likelihood of sleep disturbances, while abnormal sleep duration, in turn, contributes to further deterioration of metabolic health, potentially creating a vicious cycle.