Sleep duration has been associated with insulin resistance and metabolic disorders in prior observational analyses. A cross-sectional study published in BMJ Open Diabetes Research & Care evaluated the relationship between weekday sleep duration and insulin resistance using estimated glucose disposal rate (eGDR), while also assessing the moderating role of weekend catch-up sleep (WCS).

The analysis used data from the National Health and Nutrition Examination Survey (NHANES) collected between 2009 and 2023 and included 23,475 participants. Restricted cubic spline modeling assessed nonlinear associations between weekday sleep duration and eGDR. Piecewise regression analysis identified threshold effects, and generalized linear models together with multivariable regression models evaluated associations between weekday sleep duration categories, WCS, and eGDR.

The analysis identified an inverted U-shaped relationship between weekday sleep duration and eGDR, with an inflection point at 7.32 hours. When weekday sleep duration was below this threshold, longer sleep duration corresponded to higher eGDR (β = 0.273; 95% confidence interval [CI] 0.224-0.322; p < 0.001). When weekday sleep duration exceeded 7.32 hours, the association reversed (β = −0.222; 95% CI −0.272 to −0.171; p<0.001).

Moderation analysis showed that among individuals reporting less than 7.32 hours of weekday sleep, 1–2 hours of WCS corresponded to higher eGDR compared with no WCS (β = 0.296; 95% CI 0.107–0.484; p = 0.002). In contrast, more than 2 hours of WCS showed a negative moderating effect on the relationship between weekday sleep duration and eGDR (β =−0.568; 95% CI −0.970 to −0.167; p = 0.005). 

These findings indicate a nonlinear association between weekday sleep duration and insulin resistance measured by eGDR, with differing patterns according to the extent of weekend catch-up sleep.