Like the Omron Evolv ($75), the blood pressure cuff has the electronics embedded in the cuff itself. That can make it a little awkward to use, especially if you don’t have a particularly big arm. Aktiia also instructs you to use the cuff on the opposite arm from which you’re wearing the band. You also can’t use third-party BPMs to calibrate the cuff, to ensure Aktiia’s touted accuracy. (The Hilo was FDA-cleared in 2025, has been tested and reviewed in multiple clinical-grade studies over several years, and meets the ISO 81060-2 standard for validating the accuracy of blood pressure monitors.)

A regular BPM cuff measures your blood pressure, or how hard the blood presses against your vessel walls, by inflating the cuff to temporarily stop blood flow. Your doctor, or nowadays a digital oscillometric detector, then listens for when the blood stops and starts flowing in your veins; the highest measurement is your systolic BP, and the lowest your diastolic.

Instead of applying pressure to your blood vessels, the Hilo band uses the same photoplethysmography (PPG) optical sensors that are already in most fitness trackers to analyze the pulse shape of the arteries under your skin. It then uses its proprietary algorithm to measure your blood pressure multiple times a day when you’re at rest.

Nighttime Measurements

ScreenshotHilo via Adrienne So

Continuous blood pressure monitoring, especially while walking, sleeping, or lying down, is the gold standard for assessing your cardiovascular health. If your blood pressure doesn’t go down while you’re sleeping, that’s a strong indicator that you might have cardiovascular disease. Unfortunately, it’s really hard to relax if something is repeatedly squeezing your arm while you’re trying to sleep.

If you don’t already know you have hypertension, it’s just not a thing that many of us might think to check. I have excellent blood pressure whenever I go into a doctor’s office, so why would I ask if I can take my blood pressure lying down or overnight?

The Aktiia Hilo is extremely helpful because I can see my blood pressure dropping while I sleep. It also takes the average of your BP measurements throughout the day, rather than spot-checking at intervals. Some people, like my husband, have low blood pressure no matter what they do. Mine can spike if I read the wrong email, if I’m slightly dehydrated, or if my ankles are crossed when I’m measuring it.

I cross-tested this with the Withings BPM Vision and found that the results tallied; still, it’s nice to be able to measure without taking 30 minutes out of your day to sit and prepare.

Now that the Apple Watch has improved its battery life and you can wear it for 24 hours a day, it can also monitor your blood pressure at night. (The new Whoop band also purports to offer hypertension notifications, but it is notable that the Whoop has not attempted to clear the feature with the FDA.) But the Apple Watch can only look for patterns over a period of 30 days. It doesn’t offer consistent systolic and diastolic readings that your doctor can check.