Objective:

To investigate the trajectory of insomnia symptoms over time and their association with stroke events.

Background:

Insomnia is a frequent disorder affecting over one-third of the U.S population. However, the association between insomnia symptoms and stroke is less studied and it is unclear whether insomnia symptoms remain constant or change over time. 

Design/Methods:

We used the Health and Retirement Study from 2002 to 2020. The independent variable was insomnia symptoms classified on a scale ranging from 0 to 8 and including difficulty initiating sleep, difficulty maintaining sleep, waking up too early, and nonrestorative sleep. Repeated measures latent class analysis was used to identify subgroups among the study participants with different insomnia trajectories over time. Cox proportional hazards regression models were employed to investigate the association between the subgroup of insomnia symptoms and stroke events.

Results:

A total of 31,126 participants were included with a mean follow-up of 9 years. Three subgroups of insomnia symptoms were identified based on 3 consecutive measurements of insomnia symptoms at 2-year intervals. The subgroups were named: “constantly no symptoms”, “constantly low symptoms”, and “constantly high insomnia symptoms”. Compared to participants classified as “constantly no symptoms”, participants classified as “constantly low symptoms” had an increased risk of stroke (hazard ratio (HR) = 1.15, 95% confidence interval (CI): 1.00, 1.32). Similarly, compared to participants classified as “constantly no symptoms”, participants classified as “constantly high symptoms” had an increased risk of stroke (HR= 1.42, 95% CI: 1.22, 1.64).

Conclusions: