Study objectives: To examine the joint effect of insomnia and objective short sleep duration on hypertension risk.
Design: Representative cross-sectional study.
Setting: Sleep laboratory.
Participants: 1,741 men and women randomly selected from central Pennsylvania.
Measurements: Insomnia was defined by a complaint of insomnia with a duration > or = 1 year, while poor sleep was defined as a complaint of difficulty falling asleep, staying asleep, or early final awakening. Polysomnographic sleep duration was classified into 3 categories: > or = 6 h sleep (top 50% of the sample); 5-6 h (approximately the third quartile of the sample); and < or = 5 h (approximately the bottom quartile of the sample). Hypertension was defined based either on blood pressure measures or treatment. We controlled for age, race, sex, body mass index, diabetes, smoking, alcohol use, depression, sleep disordered breathing (SDB), and sampling weight.
Results: Compared to the normal sleeping and > 6 h sleep duration group, the highest risk of hypertension was in insomnia with < 5 h sleep duration group (OR [95% CI] 5.1 [2.2, 11.8]), and the second highest in insomnia who slept 5-6 hours (OR 3.5 [1.6, 7.9] P < 0.01). The risk for hypertension was significantly higher, but of lesser magnitude, in poor sleepers with short sleep duration.
Conclusions: Insomnia with short sleep duration is associated with increased risk of hypertension, to a degree comparable to that of other common sleep disorders, e.g., SDB. Objective sleep duration may predict the severity of chronic insomnia a prevalent condition whose medical impact has been apparently underestimated.