Different long-term sleep duration trajectories are associated with the risk of cognitive impairment in elderly Chinese individuals, indicating that monitoring dynamic changes in sleep patterns may provide early warning value for cognitive health.
Key Findings
Results
Four distinct sleep duration trajectories were identified among elderly Chinese adults over a 13-year period.
The four trajectories were: decreasing sleep duration (25.19% of participants), increasing sleep duration (50.48%), decreasing-increasing sleep duration (9.88%), and increasing-decreasing sleep duration (14.45%)
Latent class trajectory modeling was used to identify these trajectories
Sleep duration was measured at three time points: 2005, 2008, and 2011
The study included 1,882 participants from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), all aged 60 or older and without cognitive impairment at baseline
Results
Approximately 13.07% of participants developed cognitive impairment over the follow-up period.
246 out of 1,882 participants developed incident cognitive impairment
Participants were followed up in the 2014 and 2017-2018 survey waves after the trajectory assessment period (2005-2011)
Cox proportional hazards regression models were used to examine associations with incident cognitive impairment
Results
The increasing-decreasing sleep duration trajectory was associated with the highest risk of cognitive impairment compared to the decreasing sleep duration trajectory.
Multivariable-adjusted hazard ratio (HR) for increasing-decreasing sleep duration trajectory was 2.54 (95% CI: 1.67, 3.85) compared to the decreasing sleep duration trajectory
The decreasing sleep duration trajectory served as the reference group
This trajectory represented 14.45% of the study population
Results
The increasing sleep duration trajectory was associated with a significantly elevated risk of cognitive impairment.
Multivariable-adjusted HR for the increasing sleep duration trajectory was 1.63 (95% CI: 1.14, 2.32) compared to the decreasing sleep duration trajectory
The increasing sleep duration trajectory was the most common, comprising 50.48% of participants
The confidence interval did not cross 1.0, indicating statistical significance
Results
The decreasing-increasing sleep duration trajectory was associated with a significantly elevated risk of cognitive impairment.
Multivariable-adjusted HR for the decreasing-increasing sleep duration trajectory was 1.74 (95% CI: 1.08, 2.81) compared to the decreasing sleep duration trajectory
This trajectory represented the smallest proportion of participants at 9.88%
The confidence interval narrowly excluded 1.0, indicating statistical significance
Methods
The study used a nationally representative longitudinal cohort of Chinese adults aged 60 years or older spanning 13 years.
Data were drawn from the Chinese Longitudinal Healthy Longevity Survey (CLHLS)
Only participants without cognitive impairment at baseline who reported sleep duration in all three surveys (2005, 2008, and 2011) were included
Follow-up assessments occurred in 2014 and 2017-2018 survey waves
The study design allowed for prospective assessment of sleep trajectories and subsequent cognitive outcomes
What This Means
This research followed nearly 1,900 older Chinese adults (aged 60 and above) for 13 years to understand how changes in sleep duration over time relate to the development of cognitive impairment (such as dementia). Rather than just measuring sleep at one point in time, the researchers tracked sleep patterns across multiple survey waves and identified four distinct groups: people whose sleep was gradually decreasing, people whose sleep was gradually increasing, people whose sleep decreased then increased, and people whose sleep increased then decreased. About 13% of participants developed cognitive impairment by the end of the study.
The key finding was that, compared to people whose sleep duration was consistently decreasing over time, all other sleep trajectory groups had a significantly higher risk of developing cognitive impairment. The greatest risk was seen in people whose sleep first increased then decreased — they had more than twice the risk (HR 2.54) of developing cognitive impairment. People with consistently increasing sleep and those with a decreasing-then-increasing pattern also had notably elevated risks (HRs of 1.63 and 1.74, respectively).
This research suggests that how sleep duration changes over many years — not just how much someone sleeps at any one moment — may be an important signal for brain health in older adults. Tracking these long-term sleep patterns could potentially help identify elderly individuals at greater risk of cognitive decline earlier, offering an opportunity for intervention. The findings highlight the value of monitoring sleep trends over time rather than relying on single snapshots of sleep behavior.
Li R, Zhai W, Liu J. (2026). Sleep duration trajectories and cognitive impairment among elderly: a 13-year cohort study in China.. BMC geriatrics. https://doi.org/10.1186/s12877-026-07001-z