Interpreting explained variance in racial disparities in sleep health: conceptual and methodological considerations

We read with great interest the recent study by Knutson et al. [1], this research based on the CARDIA cohort, systematically examined the contributions of clinical, psychosocial, and lifestyle factors to racial disparities in sleep health among middle-aged adults. A key strength of the study lies in its integration of multidimensional objective sleep measures within a longitudinal design spanning 35 years. Through domain-specific modeling, it represents the first attempt to quantify the relative contributions of various risk factors in explaining these disparities. The methodological approach—aimed at empirically distinguishing between the existence of disparities and their underlying sources—marks a notable advance in methodology and offers a valuable analytical framework for identifying potential intervention targets in public health. However, while recognizing the study’s important contributions, we believe several aspects related to the interpretation of key findings and methodological choices warrant further discussion. Such considerations may help guide future research toward deeper exploration in this critical area.