Date Published: July 31, 2015
Publisher: Public Library of Science
Author(s): A. Katharina Helbig, Doris Stöckl, Margit Heier, Karl-Heinz Ladwig, Christa Meisinger, Raffaele Ferri.
To examine the relationship between symptoms of insomnia and sleep duration and incident total (non-fatal plus fatal) strokes, non-fatal strokes, and fatal strokes in a large cohort of men and women from the general population in Germany.
In four population-based MONICA (monitoring trends and determinants in cardiovascular disease)/KORA (Cooperative Health Research in the Region of Augsburg) surveys conducted between 1984 and 2001, 17,604 men and women (aged 25 to 74 years) were asked about issues like sleep, health behavior, and medical history. In subsequent surveys and mortality follow-ups, incident stroke cases (cerebral hemorrhage, ischemic stroke, transient ischemic attack, unknown stroke type) were gathered prospectively until 2009. Sex-specific hazard ratios (HR) and their 95% confidence intervals (CI) were estimated using sequential Cox proportional hazards regression models.
During a mean follow-up of 14 years, 917 strokes (710 non-fatal strokes and 207 fatal strokes) were observed. Trouble falling asleep and difficulty staying asleep were not significantly related to any incident stroke outcome in either sex in the multivariable models. Among men, the HR for the association between short (≤5 hours) and long (≥10 hours) daily sleep duration and total strokes were 1.44 (95% CI: 1.01–2.06) and 1.63 (95% CI: 1.16–2.29), after adjustment for basic confounding variables. As for non-fatal strokes and fatal strokes, in the analyses adjusted for age, survey, education, physical activity, alcohol consumption, smoking habits, body mass index, hypertension, diabetes, and dyslipidemia, the increased risks persisted, albeit somewhat attenuated, but no longer remained significant. Among women, in the multivariable analyses the quantity of sleep was also not related to any stroke outcome.
In the present study, symptoms of insomnia and exceptional sleep duration were not significantly predictive of incident total strokes, non-fatal strokes, and fatal strokes in either sex.
Strokes are one of the leading causes of severe disability , morbidity , and mortality  worldwide. According to estimates from the Global Burden of Disease Study, 16.9 million individuals suffered a first stroke in the year 2010. In the same year, 5.9 million stroke-related deaths occurred . Besides the serious effects for the individuals concerned, their families, and their friends, strokes can cause considerable societal costs. For Germany, projections up to the year 2025 yielded expected direct costs of 108.6 billion EUR for first ischemic strokes alone .
In the presented analyses, no associations were observed between trouble falling asleep or difficulty staying asleep and the risk of developing any stroke outcome in either sex. Among women, in the multivariable analyses the quantity of sleep was also not related to any stroke outcome. However, among men, sleeping ≤5 hours or ≥10 hours daily significantly increased the risk of developing total strokes, non-fatal strokes, and fatal strokes compared to those sleeping 7–8 hours in the unadjusted analyses. These increased risks persisted, albeit somewhat attenuated, but no longer remained significant after adjustment for a wide range of covariates, including socio-demographic aspects, health status, several diseases, and medical history.
In conclusion, the results suggest that trouble falling asleep and difficulty staying asleep are not associated with incident total strokes, non-fatal strokes, or fatal strokes in either sex. There is an increased risk especially for fatal strokes in men with short and long sleep duration, albeit insignificant. Further research should explore the role of a combined effect of symptoms of insomnia and short sleep duration in association with incident strokes taking into account the sex- and gender-specific particularities regarding this issue.