Smartwatch Health Alerts: How to Use Fitness Tracker Data Without Worry

You’re in the middle of a busy workday and you feel a buzz on your wrist. A notification from your smartwatch says your heart rhythm looked irregular. Now what?

Almost 1 in 3 Americans uses a wearable device to track health and fitness, according to the National Heart, Lung, and Blood Institute.  

Whether it's a watch, ring, or band, a wearable device can nudge you to move, monitor your sleep, and help you spot health changes over time. It can also alert you when one of those areas may need attention. In most cases, these alerts are helpful—if you understand what they can tell you and when to ask an expert for context.

If an alert you received about your heart, sleep, or overall health has you worried, use it as a cue to check in with your health care provider. Be sure to save a screenshot of any notification you want to share with your provider. And keep in mind that a quiet device doesn't always mean everything is fine.

"I think of a wearable as a really good notebook,” says Diana Westerfield, DO, a BJC Medical Group cardiologist. “It remembers how you slept last Tuesday, but it can't know you. The most useful part of your data is often what you tell me along with it, like if you felt palpitations or were lightheaded at the time of the alert.”

Where wearables shine

Adults need at least 150 minutes of moderate aerobic activity each week, plus muscle-strengthening activity at least two days a week, according to the U.S. Department of Health and Human Services. In 2024, less than 27% of U.S. adults met both goals.  

A wearable that counts your steps doesn’t do the work for you, but it does make progress visible, trackable, and even sharable for those who want exercise partners or personal trainers to help hold them accountable.

Just as it can track your exercise, wearables can also flag when something seems off with your heartbeat, sleep, or blood pressure.

Under guidance the U.S. Food and Drug Administration (FDA) updated in January 2026, devices like wearable fitness trackers that help promote a healthy lifestyle generally are not regulated as medical devices. But the FDA has authorized certain over-the-counter wearable features as medical devices, including:

• Irregular heart rhythm notifications, such as atrial fibrillation (a-fib)
• A sleep apnea risk feature
• A high blood pressure notification feature

It’s important to remember that even FDA-authorized features aren't meant to diagnose conditions. A timely alert can help someone get the right care, while a false alert can lead to unnecessary stress and anxiety.

Where context is important

Other heart conditions: Most wearables use light-based sensors that are good at spotting an uneven heartbeat. But some heart rhythm conditions keep a steady beat, and wearables are much less reliable at identifying those. One example is supraventricular tachycardia (SVT), a fast heart rate that starts in the heart's upper chambers and may come and go.  

Blood sugar: The FDA hasn't authorized any smartwatch or ring to measure blood sugar on its own. Inaccurate readings could lead to the wrong medication dose and dangerously low blood sugar. This doesn't apply to watch apps that display data from FDA-authorized continuous glucose monitors that pierce the skin.

Blood pressure: Nearly half of U.S. adults, about 122 million people, have high blood pressure, according to the American Heart Association (AHA). Yet cuffless devices, including smartwatches and rings, aren't proven accurate enough to diagnose high blood pressure or guide treatment. For home checks, the AHA recommends an automatic, validated, upper-arm cuff monitor. If you have one, bring it to your next doctor’s appointment so your care team can check its accuracy and fit.

Oxygen levels: Evidence suggests pulse oximeter accuracy can differ by skin pigmentation, according to the FDA.

How to respond to an alert

First, pay attention to how you feel. If you are feeling ill when your device sounds, seek immediate medical attention. If you experience the warning signs of a heart attack, such as chest discomfort or shortness of breath, call 911 right away whether you received an alert from your wearable or not.  

If you feel fine, take these steps:

• Keep taking any prescribed medication as directed. Don't start, stop, or change any medicine based on a device reading without talking with your provider.
• Screenshot the alert and write down what you were doing when it happened.
• Contact a trusted health care provider to talk through your next steps.

“An alert can make your own heart race, and that's a normal reaction,” Dr. Westerfield says. “I would start with questions, not tests. Did you just finish a workout or a third cup of coffee? Those answers help us decide together what actions, if any, are necessary.”  

Knowing what's typical can also take some of the worry out of the numbers.

For most adults, a normal resting heart rate is 60 to 100 beats per minute, according to the AHA. Stress, anxiety, hormones, medicine, and activity level can all affect resting heart rate, and very active people may rest as low as 40 beats per minute.

If constantly tracking your data makes you feel anxious, try adjusting the settings on your device and relying on weekly reports instead of daily updates.

“Checking your data frequently during the day can make you more anxious, and then your heart rate or blood pressure can increase as a result,” Dr. Westerfield says. “It can be a vicious cycle.”

Make your doctors your data partners

The National Institutes of Health describes wearables as tools people can use in partnership with their health care providers.

At your next doctor’s visit, bring screenshots of any alerts, a few weeks of trend data, and your home blood pressure monitor if you use one.

"Some of my best visits start with a patient saying, 'Here's what I've noticed,’” Dr. Westerfield says. “A month of data tells me a lot more about what your life really looks like, and we can work together to use that information to help set goals you can keep.”

Your smartwatch can provide data, but it can't replace expert guidance. Consider your health care providers as teammates who can help keep you safe. If you have questions about heart rhythm alerts, blood pressure readings, or other heart health concerns, BJC HealthCare heart and vascular specialists can help you understand what the numbers mean and what steps, if any, you should take next. Learn more about heart and vascular care.  

Does your wearable track VO2 max? It can help measure your cardiorespiratory fitness, and it’s one of four health metrics that can help predict how well you’ll age. Read about VO2 max and more important metrics.