Are you stress free? Check your Apple Watch.

Apple Watch has a feature that tracks your stress levels. And a new study suggests that it actually works not just to detect your stress level, but to predict it as well. Or, your Apple Watch can predict when you’re not stressed—it’s kind of stressed.

The existing feature allows Apple Watch owners to take an electrocardiogram — also known as an ECG or EKG — directly through their watch through the ECG app. ECG tests record the timing and strength of your heartbeat; This is a test that doctors use to learn about your heart rate and detect irregularities. According to the Society of Nuclear Medicine and Molecular ImagingDoctors regularly use ECGs to perform stress tests, so it’s no surprise that Apple wants to add ECG capabilities to their new technology.

“The ECG app records your heart rate and rhythm with the electrical heart sensor on the Apple Watch Series 4, Series 5, Series 6, Series 7, Series 8 or Ultra, and checks the recording for an irregular pattern of atrial fibrillation (AFib). Rhythm,” According to Apple Support. “The ECG app records an electrocardiogram that represents the electrical impulses that make your heart beat. The ECG app checks these impulses to get your heart rate and see if the upper and lower chambers of your heart are in rhythm. Rhythm, it could be AFib.”

It’s not clear how useful Apple Watch ECG readings are in tracking stress. But a new study shows that the ECG feature — along with other metrics on the Apple Watch — serves as a basic stress diagnostic tool and can even be used to predict stress. According to a study published in the journal Frontiers of Digital Health“Current models have high specificity, predicting ‘no pressure’ conditions relatively well, [but] So far it lacks the predictive power to accurately predict ‘stress’ levels.”

“Overall, the results presented here, and with further development and refinement, Apple Watch ECG sensor data can be used to develop a stress prediction tool,” the article states. “A wearable device capable of continuous, real-time stress monitoring could enable individuals to proactively respond to changes in their mental health. Also, large-scale data collection from such devices could inform public health initiatives and policies.”

But all that extra information about our stressors can make us even more stressed.

Lindsey Rossman, a clinical health psychologist and assistant professor of cardiology at the University of North Carolina at Chapel Hill, Found in a research paper A 70-year-old woman with atrial fibrillation performed nearly 1,000 ECGs on her watch in one year. The additional data did not lead to any changes in the patient’s medical treatment, but continued use of her watch and fear and anxiety related to her health “had a profound negative impact on her mental health, relationships and quality of life.”

This is, obviously, a pretty extreme example of how technology can increase our stress levels, but it’s not an isolated incident. Another study From the University of Copenhagen, they found that nudges from their Fitbit tracker were more stressful than anything else for many users.

So, the Apple Watch can do what Apple says: track our every pressing move. But do we like it? Is it really that good?