Background <p>Single-measure sleep duration has been extensively studied in association to cognitive impairment. However, this approach overlooks the potential impact of long-term sleep duration trajectories on cognitive function. The present study aims to identify distinct long-term sleep duration trajectories and prospectively assess their association with the risk of cognitive impairment in Chinese elderly individuals.</p> Methods <p>This study utilized data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), a nationally representative cohort of adults aged 60 years or older. Participants without cognitive impairment at baseline who had reported their sleep duration in all three surveys (2005, 2008, and 2011) were included. These participants were subsequently followed up in the 2014 and 2017–2018 survey waves. Sleep duration trajectories were identified using latent class trajectory modeling, and Cox proportional hazards regression models were employed to examine their association with the risk of incident cognitive impairment.</p> Results <p>A total of 1,882 participants were included in this study, of whom approximately 246 (13.07%) developed cognitive impairment. Four distinct sleep duration trajectories were identified: decreasing sleep duration (25.19%), increasing sleep duration (50.48%), decreasing-increasing sleep duration (9.88%), and increasing-decreasing sleep duration (14.45%). Compared with the decreasing sleep duration trajectory, the multivariable-adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) for the increasing sleep duration trajectory, decreasing-increasing sleep duration trajectory, and increasing-decreasing sleep duration trajectory were 1.63 (1.14, 2.32), 1.74 (1.08, 2.81), and 2.54 (1.67, 3.85), respectively.</p> Conclusion <p>Different sleep duration trajectories are associated with the risk of cognitive impairment, indicating that monitoring dynamic changes in sleep patterns may provide early warning value for cognitive health in the elderly.</p>