The saturation effect of 25(OH)D level on sleep duration for older people:The NHANES 2011–2018

This study aimed to investigate the potential relationship between vitamin D and sleep duration in older adults. The study utilized multivariate linear regression models to estimate the associations between serum 25(OH)D and sleep duration. In addition, a smooth curve fitting approach was used to identify any non-linear trends between the two variables. The study included 15,749 participants over the age of 60. The results showed a positive correlation between serum 25(OH)D levels and sleep duration in the fully-adjusted model. This correlation was observed in both males and females, as well as in non-Hispanic White and non-Hispanic Black participants. No significant interactions were found between serum 25(OH)D levels and the stratifying variables. The curve fitting analysis revealed a non-linear relationship between 25(OH)D and sleep duration, with a saturation point observed at a serum 25(OH)D level of 40.6 ng/mL. In conclusion, the findings suggest that there is a positive correlation between serum 25(OH)D levels and sleep duration, with a saturation effect observed. A positive correlation is evident when serum 25(OH)D falls below 40.6 ng/mL.