Insomnia with objective short sleep duration and incident hypertension: The Penn State Cohort

Insomnia with objective short sleep duration appears to be a biologically more severe phenotype of the disorder. No longitudinal study to date has examined the association of this type of insomnia with incident hypertension using polysomnography. From a random, general population sample of 1741 adults of the Penn State Cohort, 1395 were followed-up after 7.5 years, and 786 did not have hypertension at baseline. Hypertension was determined by a self-report of receiving treatment for high blood pressure. Chronic insomnia was defined as a complaint of insomnia lasting ≥1 year, whereas poor sleep was defined as moderate-to-severe sleep difficulties. All of the subjects underwent 8-hour polysomnography. Sleep-disordered breathing (SDB) was defined as an obstructive apnea/hypopnea index ≥5. We used the median polysomnographic percentage of sleep time to define short sleep duration (ie, <6 hours). We controlled for sex, race, age, caffeine, cigarettes and alcohol consumption, depression, sleep-disordered breathing, diabetes mellitus, obesity, and blood pressure in our analyses. Compared with normal sleepers who slept ≥6 hours, the highest risk for incident hypertension was in chronic insomniacs with short sleep duration (odds ratio, 3.8 [95% CI, 1.6-9.0]). The risk for incident hypertension in poor sleepers with short sleep duration was significantly increased but became marginally significant after controlling for obesity (odds ratio, 1.6 [95% CI, 0.9-2.8]). Chronic insomnia with short sleep duration is associated with an increased risk for incident hypertension in a degree comparable to sleep-disordered breathing. Objective short sleep duration in insomnia may serve as a useful predictor of the biological severity of the disorder.