Getting about seven hours of sleep each night may help protect against insulin resistance, according to a new study published online on March 3 in BMJ Open Diabetes Research & Care.

Researchers led by Zhanhong Fan from the School of Nursing and Rehabilitation at Nantong University in China examined the relationship between weekday sleep duration and metabolic health using data from 23,475 participants in the U.S. National Health and Nutrition Examination Survey collected between 2009 and 2023.

The team focused on the estimated glucose disposal rate (eGDR), a measure commonly used to assess insulin resistance. Their analysis revealed an inverted U-shaped relationship between weekday sleep duration and eGDR, suggesting that both too little and too much sleep may negatively affect metabolic health.

The study identified an optimal sleep duration of about 7.32 hours per night. When individuals slept less than this threshold, increasing sleep duration was associated with improved eGDR levels, indicating better insulin sensitivity. However, sleeping longer than the identified threshold showed an opposite effect, with extended sleep linked to lower eGDR levels and potentially higher insulin resistance.

The researchers also examined the impact of weekend catch-up sleep among individuals who slept less than the recommended duration during weekdays. They found that sleeping one to two additional hours on weekends was associated with improved eGDR levels compared with those who did not compensate for lost sleep. However, extending weekend sleep by more than two hours appeared to weaken the positive effects and was linked to poorer metabolic outcomes.

According to the researchers, the findings highlight a complex relationship between sleep and metabolic health. They note that poor sleep patterns and metabolic dysfunction may reinforce each other.

“There appears to be a bidirectional relationship between sleep and metabolism,” the authors wrote. “This creates a potential vicious cycle wherein metabolic dysregulation disrupts normal sleep patterns, and the resultant abnormal sleep, including extended duration, further aggravates metabolic health.”

The researchers say the findings underscore the importance of maintaining consistent and balanced sleep habits as part of strategies to reduce the risk of metabolic disorders such as insulin resistance.