A nationally representative United States study found an inverted U-shaped relationship between weekday sleep duration and insulin sensitivity, with approximately 7.3 hours of sleep associated with the most favorable metabolic profile. Both shorter and longer sleep durations were linked to lower insulin sensitivity.
The analysis also found that moderate weekend catch-up sleep (WCS) was associated with higher metabolic marker levels among adults with shorter weekday sleep, while excessive catch-up sleep showed no significant direct association with metabolic markers but modified the relationship between weekday sleep duration and insulin sensitivity. The findings were published in BMJ Open Diabetes Research & Care.
Study Design
Investigators analyzed data from 23,475 United States adults aged 20 years or older participating in the National Health and Nutrition Examination Survey (NHANES) between 2009 and 2023.
Participants with missing sleep or metabolic data, pregnancy, or incomplete covariate information were excluded.
Weekday sleep duration was self-reported as typical hours slept on workdays. Weekend catch-up sleep was defined as the difference between weekend and weekday sleep duration and categorized as:
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no catch-up sleep
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greater than 0 to 1 hour
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greater than 1 to 2 hours
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greater than 2 hours
Weekend sleep data were available for 10,817 participants from the 2017–2023 NHANES cycles, who were included in analyses examining catch-up sleep.
Insulin resistance was assessed using the estimated glucose disposal rate (eGDR), a marker calculated from waist circumference, hypertension status, and glycated hemoglobin levels. Lower eGDR values indicate poorer insulin sensitivity.
Nonlinear Relationship Between Sleep and Metabolism
Using restricted cubic spline modeling, investigators identified a sleep-duration inflection point at 7.32 hours, which was associated with the highest eGDR levels.
Among participants sleeping less than 7.32 hours, each additional hour of weekday sleep was associated with a 0.273-unit increase in eGDR, indicating improved insulin sensitivity.
In contrast, among participants sleeping 7.32 hours or more, each additional hour of sleep was associated with a 0.222-unit decrease in eGDR, suggesting lower insulin sensitivity with longer sleep duration.
Weekend Catch-up Sleep
The association between WCS and eGDR differed according to weekday sleep duration.
Among participants sleeping less than 7.32 hours on weekdays, moderate WCS was associated with higher eGDR compared with no catch-up sleep:
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0 to 1 hour of catch-up sleep was associated with a 0.249-unit increase in eGDR
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1 to 2 hours of catch-up sleep was associated with a 0.296-unit increase in eGDR
Catch-up sleep greater than 2 hours was not significantly associated with eGDR in this group.
Among participants sleeping 7.32 hours or more on weekdays, WCS was not significantly associated with eGDR.
However, moderation analyses showed that catch-up sleep exceeding two hours strengthened the negative relationship between longer weekday sleep duration and eGDR.
Subgroup Findings
Subgroup analyses identified demographic differences in the association between longer sleep duration and insulin sensitivity.
Among participants sleeping at least 7.32 hours on weekdays, longer sleep duration was associated with lower eGDR particularly among:
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women
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adults aged 40 to 59 years
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individuals with obesity (body mass index ≥30)
Among participants sleeping less than 7.32 hours, longer sleep duration was generally associated with higher eGDR across demographic groups.
Limitations
The investigators noted several limitations. The cross-sectional design prevents causal inference, and sleep duration was self-reported, which may introduce recall bias.
Residual confounding from factors such as sleep quality, mental health status, medication use, or shift work could not be excluded. The study also could not distinguish between nighttime sleep and daytime napping.
Despite these limitations, the findings suggest sleep patterns may be relevant to metabolic health and insulin sensitivity.
“Among individuals with shorter weekday sleep, modest WCS (≤2 hours) was linked to higher eGDR, whereas excessive WCS showed a negative association with eGDR,” wrote lead author Zhanhong Fan of the School of Nursing and Rehabilitation at Nantong University in China, and colleagues.
The researchers reported no competing interests.
