High blood pressure (hypertension) is the most common condition of the circulatory system. The condition is often called a ‘silent killer’ because it can go undetected if blood pressure isn’t checked and can result in heart conditions and stroke. According to the Heart Foundation, 32% of Australians aged 18 years and over have high blood pressure, which is defined as systolic or diastolic blood pressure that is greater than 140/90 mmHg.
One hypothesis is that the poor sleep and/or a lack of sleep may contribute to persistent high blood pressure. Various studies conducted on the relationship between sleep and hypertension support this idea. For example, a study presented at an American Heart Association conference found a strong link between sleep quality and a type of blood pressure called resistant hypertension, which does not respond to common drug treatments. In addition, the research found that women with resistant hypertension were five times more likely to have poor sleep quality than women without the condition. In the study, the average sleep time was only 6.4 hours per night, but it was the sleep quality, not quantity, that seemed to influence the risk of having high blood pressure.
While this research only uncovered a connection between poor sleep and hypertension, other studies have shown a link between a lack of deep sleep and hypertension in men.
In another study, the sleep quality and blood pressure of nearly 800 men over the age of 65 were monitored. The results showed a strong connection between the lack of Slow Wave Sleep (SWS) and elevated blood pressure. Slow Wave Sleep is the final stage of non-REM (Rapid Eye Movement) sleep that is marked by low heart and respiratory rates. During Slow Wave Sleep the body uses its resources to regenerate tissues, build bones and muscle, recharge energy stores and strengthen the immune system.
Other research points to the link between the duration of sleep and blood pressure. One example is the Sleep Heart Health Study which showed a strong connection between less sleep and hypertension. The authors concluded ‘Usual sleep duration above or below the median of 7 to less than 8 hours per night is associated with an increased prevalence of hypertension, particularly at the extreme of less than 6 hours per night.’
Study presented at the American Heart Association High Blood Pressure Research 2012 Scientific Sessions, Los Angeles, CA, November 3-7, 2012
Maple M. Fung, Katherine Peters, Susan Redline, Michael G. Ziegler, Sonia Ancoli-Israel, Elizabeth Barrett-Connor, Katie L. Stone, for the Osteoporotic Fractures in Men Research Group, Decreased Slow Wave Sleep Increases Risk of Developing Hypertension in Elderly Men.