An app for tracking your vitals

Your phone can be a simple way to keep an eye on your health. With the right app, you can log your vital signs and get a clearer picture of what's going on.

But let's get one thing straight. Most of these apps don't actually measure anything. Your phone's camera isn't a medical device. Think of these apps as a digital diary. You take a measurement with a blood pressure cuff or a pulse oximeter, and then you log the number in the app.

The real value is in the trends.

Seeing your numbers plotted over a few weeks or months helps you and your doctor spot patterns that are easy to miss. An app just organizes everything in one place.

What actually matters in a tracking app

Some apps are just simple logs. Others do a lot more.

You should be able to type in your numbers easily. Some apps can also sync with Bluetooth devices, which is faster and means no typos. It's also better to find an app that can track everything you need—blood pressure, heart rate, oxygen, glucose, whatever—in one place. And it needs to show you the data in simple charts and graphs, otherwise, it's just a list of numbers.

The hardest part is being consistent. Apps that have reminders can help. Some, like the Trider app, use "streaks" to get you to build a daily habit, which is what this is all about. Most importantly, you need to be able to export your data. If you can't easily share a PDF with your doctor, the app isn't that useful.

Can the camera really be a sensor?

A few new apps are trying to use the phone's camera to estimate vitals.

You just press your finger against the lens, and the app watches for tiny changes in color as your blood pulses. It uses that to guess your heart rate and sometimes blood oxygen.

I tried one of these while waiting for a train the other day. The heart rate it gave me was surprisingly close to what my watch said. It's not a replacement for a real medical device, but it's interesting that some companies are getting FDA clearance for this kind of tech.

It's about the habit, not the app

An app is just a tool. The goal is to build the habit of checking in on your health, whether you're managing a condition or just trying to be careful.

The technology is impressive, but the best app is the one you actually open and use. Find one that's simple enough that you won't get tired of it, and just start logging.