Getting too little sleep and not sleeping well can contribute to high blood pressure in middle-aged men and women, according to a study published June 8 in the Archives of Internal Medicine. This observation may lead to treatments that target sleep behavior in order to treat or prevent high blood pressure.
One in 3 American adults has high blood pressure, including 36 million women. High blood pressure increases your risk of dying early or having a heart attack, stroke, or heart failure. It is estimated that controlling blood pressure could prevent one third of heart disease problems in women.
Earlier survey-based studies have found that people who sleep less tend to have higher blood pressure. This study was the first to supplement surveys about sleeping habits with actual data from a wrist sensor, and also the first to attempt to determine the effect of sleep quality (in addition to quantity) on blood pressure.
The study followed 578 African American and white participants between 33 and 45 years old (47% were women). Over a 5-year period, researchers monitored blood pressure, the amount of sleep a person got each night, and sleep maintenance (the percentage of time between going to bed and getting up that was actually spent sleeping).
The average person in the study slept 6 hours a night and was awake 11% of the time after falling asleep. The less a person slept, the higher their blood pressure numbers: each hour of extra sleep resulted in a 37% lower chance of developing high blood pressure. People who had spent more time awake during the night also had higher blood pressure numbers and their blood pressure increased more over time. Even after adjusting for other factors like age, race, sex, weight, and alcohol use, people who got less sleep consistently had higher blood pressure, a finding that held true for both women and men regardless of race.
How does lack of good sleep cause high blood pressure? Laboratory studies have found that short-term sleep deprivation activates the sympathetic nervous system, responsible for the "fight or flight" response. Among other things, activation of this system increases heart rate and blood pressure. It could be that long-term sleep shortages cause long-term activation of the system (much like chronic stress does), leading to high blood pressure.
Interestingly, although snoring was less common in women in this study (11% compared to 17% of men), women who did snore had 5 times the risk of developing high blood pressure compared with women who did not snore. Men who snored did have an elevated risk. Although the reason for this is not known, the authors speculate that it could be related to gender differences in sleep apnea—pauses in breathing during sleep that can eventually damage the heart and blood vessels.
Standard treatment of high blood pressure begins with lifestyle changes, including a healthy diet and regular exercise; if these are not enough, medication to lower blood pressure may be necessary. If the results of this study are confirmed in further studies, sleep management may be added to the standard list of lifestyle changes to treat and prevent high blood pressure, one of the most important heart disease risk factors. More studies are needed to prove that better sleep habits can actually lower blood pressure over time.
Source: Knutson KL, Van Cauter E, et al. Association between sleep and blood pressure in midlife. The CARDIA sleep study. Arch Intern Med. 2009;169(11):1055-1061