Normally, blood pressure readings at night are known to record values 10-20% below daytime readings. But in some cases, blood pressure may not go down even at night, and may even even exceed daytime blood pressure. The Japanese Society of Hypertension’s (JSH) Guidelines for the Management of Hypertension 2019 define nocturnal hypertension as an average systolic nocturnal blood pressure reading (while asleep) of 120mmHg or higher and/or a diastolic nocturnal blood pressure over 70mmHg.

Study findings confirm increased stroke risk

A study by Professor Kazuomi Kario’s group at Jichi Medical University resulted in the following findings after some seven years: For a group with high average nocturnal systolic blood pressure readings (132.3mmHg or higher), stroke incidence increased by a factor of 5.4 times compared to a normal blood pressure group (108.7-116.3mmHg).¹

Prevalence of nocturnal hypertension

Nocturnal hypertension can often be overlooked, even for those who regularly take blood pressure readings in the morning and evening, because blood pressure changes constantly throughout the day. Study reports showed that nearly one in four patients with normal morning blood pressure had nocturnal hypertension.²

Fighting the hidden risk

The risk of nocturnal hypertension can remain unseen even with appropriate blood pressure control. To enable everyone to monitor nocturnal blood pressure at home and become aware of its risk, OMRON Healthcare has been committed to developing a home-use nocturnal blood pressure monitor, as we endeavor to reduce the incidence of cerebrovascular and cardiovascular diseases caused by high blood pressure to Zero.

Neither an ambulatory blood pressure monitor (ABPM) commonly used for nocturnal blood pressure monitoring, nor a very popular upper arm monitor is easy to use when an individual is sleeping. These products and their techniques for use disrupted sleep due to the cuff’s restrictive feel, the monitor’s pumping noise, and the tube getting in the way. These conditions can result in blood pressure values that could differ from the “true” values when the person is asleep. There may also be some stress from having to use a blood pressure monitor and this may even interfere with blood pressure monitoring continuity.

This points to the need for a monitor capable of accurate blood pressure measurement while maintaining satisfactory sleep quality. With this in mind, we developed a new wrist nocturnal blood pressure monitor that features silent pumping action and a slim design.

During product development, we faced the difficult challenges of the individual’s movements during sleep. The OMRON proprietary wrist-cuff design was a solution, ensuring proper measurements without disturbing sleep.

The quest for early detection and treatment of nocturnal hypertension revolves around various challenges. The first is that we need to increase awareness of nocturnal hypertension risk and the importance of blood pressure monitoring at night. It is also necessary to encourage the medical community to recognize the significance of home-monitoring of nocturnal blood pressure and to establish standard approaches to nocturnal hypertension treatment. As we tackle these challenges, we are proactively engaged with research studies and educational activities on nocturnal hypertension.

To date, OMRON Healthcare has revolutionized blood pressure monitoring, transitioning it from a clinical practice conducted at a hospital to a daily at-home habit, and also changing the measurement frequency from “once a day” to “twice a day,” in the morning and evening. To bring Zero Events closer to reality, we will be promoting nighttime blood pressure monitoring.