According to new research, people who experience high blood pressure while they sleep are more likely to have a higher risk of stroke and heart disease. The study, published in the American Heart Association’s journal Circulation, has found that nighttime blood pressure is increasingly being recognized as a predictor of cardiovascular risk.
It is a regular procedure for doctors to use in-office and daytime blood pressure measurements to determine a patient’s blood pressure reading. However, many patients may suffer from high blood pressure while they sleep, called nocturnal hypertension. This study was one of the first of its kind to study the risk associated with high nighttime blood pressure.
Researchers analyzed 6,359 patients from across Japan between 2009 and 2017 for the study by using an at-home, wearable ambulatory monitor. All participants were part of the Japan Ambulatory Blood Pressure Monitoring Prospective (JAMP) study and had their blood pressure measured daily during activities and sleep for at least 24-hours at a time. All participants had at least one cardiovascular risk factor, and three-quarters of them were taking blood pressure medications. None had symptomatic heart disease when the study began.
All participants were required to rest or sleep during regular nighttime hours and to maintain their usual daytime activities. A diary was used to record the time they fell asleep and woke up to determine nocturnal blood pressure readings.
The follow-up for each participant occurred annually, ranging from two to seven years. The rates of cardiovascular disease events were recorded and analyzed, including stroke, heart attack, heart failure, and death. There was a total of 306 cardiovascular events, including 119 strokes, 99 diagnoses of coronary artery disease, and 88 diagnoses of heart failure. Researchers used these findings to determine any associations between the timing of heart events in relation to blood pressure variations.
The researchers concluded that increased levels during sleep (a systolic blood pressure measuring 20 mm Hg above a person’s daytime systolic reading) were significantly associated with the risk of atherosclerotic cardiovascular disease and heart failure. Those who did not stick to a structured sleep pattern were at particular risk for developing heart failure and had a greater risk of experiencing any cardiovascular disease events. An excessive reduction of blood pressure during sleep was also found to be potentially detrimental.
“Results indicate that nighttime systolic blood pressure was a significant, independent risk factor for cardiovascular events,” said Kazuomi Kario, M.D., Ph.D., lead author of the study. “The study highlights the importance of including nighttime blood pressure monitoring in patient management strategies and will hopefully encourage physicians to ensure that antihypertensive therapy is effectively lowering blood pressure throughout the 24-hour dosing period.”
This study focused on systolic rather than diastolic measurements due to the older age of the participants. Researchers name this as a study limitation along with the lack of echocardiograms, thus preventing some degree of differentiation for types of heart failure. Further research is needed to clarify these findings, which researchers hope can help physicians ensure steady blood pressure reading from their patients both during daily activities and during the night.