Associations of concurrent insomnia symptoms and excessive daytime sleepiness with mortality and incident cardiovascular disease.

OBJECTIVES

Excessive daytime sleepiness commonly co-occurs with insomnia symptoms, yet their joint association with long-term outcomes is unclear. To examine the joint associations of insomnia symptoms and excessive daytime sleepiness with all-cause mortality, cardiovascular disease mortality, and incident cardiovascular disease (defined as coronary heart disease, stroke, myocardial infarction, and heart failure).

METHODS

We analyzed 495,398 UK Biobank participants with valid baseline sleep data. Insomnia symptoms and excessive daytime sleepiness were self-reported and combined into 4 phenotypes: neither insomnia symptoms nor excessive daytime sleepiness, insomnia symptoms only, excessive daytime sleepiness only, and insomnia symptoms+excessive daytime sleepiness. Outcomes were ascertained via linkage to national registries. Cox models estimated adjusted hazard ratios (HRs), and both additive (RERI, AP) and multiplicative (product-term) interactions were assessed.

RESULTS

Over a mean follow-up of 14.9 years, totaling 7.46 million person-years, there were 51,926 deaths (10,854 cardiovascular disease deaths) and 51,299 incident cardiovascular disease events. In multivariable models, insomnia symptoms+excessive daytime sleepiness was associated with higher risks of all-cause mortality (HR 1.32, 95% CI 1.25-1.40), cardiovascular disease mortality (1.28, 1.14-1.43), and incident cardiovascular disease (1.40, 1.32-1.49) versus the reference. Insomnia symptoms only and excessive daytime sleepiness only showed modest risk elevations, whereas additive interaction between insomnia symptoms and excessive daytime sleepiness was evident for all-cause mortality (RERI 0.19, 95% CI 0.09-0.30; AP 0.14, 0.07-0.20) and cardiovascular disease incidence (RERI 0.20, 0.08-0.31; AP 0.14, 0.01-0.28).

CONCLUSIONS

The co-occurrence of insomnia symptoms and excessive daytime sleepiness was associated with higher risks of all-cause, cardiovascular disease mortality and incident cardiovascular disease than either symptom alone. These findings support considering combined sleep-symptom profiles in risk assessment, while further studies are needed to clarify underlying mechanisms and determine clinical implications.