The original dataset for exploring the trajectories of nighttime sleep duration and their association with frailty among middle-aged and older adults.

This dataset was derived from the China Health and Retirement Longitudinal Study (CHARLS, 2011–2018). It includes longitudinal data on nighttime sleep duration, frailty index, and relevant covariates for middle-aged and older adults. Baseline demographic and lifestyle characteristics (e.g., age, gender, education, marital status, residence, BMI, smoking, alcohol consumption, physical activity, income, social participation, and chronic pain) were included. The dataset was used to explore the trajectories of nighttime sleep duration and their associations with frailty among Chinese older adults.