Less Sleep Associated With High, Worsening Blood Pressure in Middle Age
Middle-aged adults who sleep fewer hours appear more likely to be hypertensive and to experience adverse changes in blood pressure over time, according to a report in the Archives of Internal Medicine. Epidemiologic studies previously reported an association between self-reported short sleep duration and increased blood pressure. Kristen L. Knutson, PhD (University of Chicago) and colleagues studied 578 adults (average age 40.1 years, 59% white) participating in the Coronary Artery Risk Development in Young Adults (CARDIA) study, The ongoing CARDIA study, which is supported by the National Heart, Lung, and Blood Institute, recruited black and white adults aged 18-30 years in 4 US cities between 1985 and 1986. The patients studied by Dr. Knutson's group were examined at the Chicago site. No patients were taking antihypertensive medication. Participants had their blood pressure measured in 2000 and 2001, as part of the CARDIA year-15 examination, and in 2005 and 2006, as part of the year-20 examination. Sleep was measured twice using wrist actigraphy for 3 consecutive days between 2003 and 2005.
Participants slept an average of 6 hours per night; almost half (43%) slept < 6 hours and only 7 (1%) averaged ≥ 8 hours of sleep. Over 5 years, on average, SBP increased (4.3 mmHg) and DBP decreased (2.6 mmHg), and 14% of participants developed hypertension. After adjustment for age, race, and gender, analyses revealed that shorter sleep duration or lower sleep maintenance predicted significantly higher levels of SBP and DBP levels cross-sectionally as well as more adverse changes in SBP and DBP levels over 5 years (all P < .05). Short sleep duration also predicted significantly increased risk (odds ratio 1.37) for hypertension. Each hour of reduction in sleep duration was associated with a 37% increase in the odds of incident hypertension. Adjustment for 16 additional covariates, including snoring and daytime sleepiness, reduced the associations between sleep and blood pressure but most remained statistically significant.
Higher blood pressure levels were observed in men than in women, particularly black men, who also slept much less than white women, "These 2 observations suggest the intriguing possibility that the well documented higher blood pressure in African Americans and men may be partly related to sleep duration," the investigators suggest.
"Identifying a novel lifestyle risk factor for high blood pressure could lead to new interventions to prevent or reduce high blood pressure," the investigators say. "Laboratory studies of short-term sleep deprivation have suggested potential mechanisms for a causal link between sleep loss and hypertension." Sleep loss may lead to increased sympathetic nervous activity, which could increase blood pressure if sleep loss were chronic, the researchers suggest. "In summary, the present study provides evidence for a link between the duration and quality of sleep and high blood pressure levels using objectively measured sleep characteristics," they conclude. "Intervention studies are needed to determine whether optimizing sleep duration and quality can reduce the risk of increased blood pressure."
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