Why Does Nighttime BP Matter?

November 2020

Measuring blood pressure at night is notoriously difficult. Home blood pressure cuffs and most new cuffless technologies require you to sit in a particular position and trigger a measurement, which won’t work when you’re asleep. Another option is ambulatory blood pressure monitors (ABPM’s), which includes a control unit that automatically inflates a cuff every 20-30 minutes; but this disturbs sleep and can impact the measurement. Aktiia is unique because our solution measures without cuff inflation and is automatically triggered, so we can measure nighttime blood pressure without disturbing sleep.

But why is it important to know what happens to our blood pressure during sleep anyway? Normally, doctors would expect to see a 10% to 20% drop in blood pressure from daytime to nighttime values, called a nocturnal dip. If your blood pressure does not drop at night, then this is called non-dipping. Multiple studies have shown that non-dipping is a “strong, independent predictor of cardiovascular risk.

An example of 24 hour blood pressure profile showing a systolic and a diastolic nighttime dip. The data was recorded by Aktiia on one user over 30 consecutive days and nights.

In the Dublin outcome study, nighttime blood pressure predicted overall cardiovascular risk better than daytime blood pressure readings at home or readings at the doctor’s office. The Ohasama study resulted in even clearer numbers: there was a 20% increased risk of cardiovascular mortality for every 5% deficiency in normal nighttime dipping. The recent Japan Ambulatory Blood Pressure Monitoring Prospective study similarly showed a strong correlation between lack of a nighttime dip in systolic BP and higher cardiovascular disease risk, in particular heart failure.

Measuring blood pressure at night can help you better understand your cardiovascular health so you can work with your doctor to create a personalized action plan. At Aktiia we’re excited to get to market soon (pending regulatory clearances), and start empowering people with this critical missing piece of information.