Your watch knows you're sick before you do: Science confirms it

What until recently seemed like science fiction is now a reality backed by science. The smart watches and rings that many people use to count steps or monitor sleep are demonstrating an astonishing ability: detecting illnesses like COVID-19, the flu, and even serious heart conditions before a person feels ill.

Multiple studies published in prestigious scientific journals such as PNAS Nexus and PLOS One have validated the potential of these devices as early warning tools in public health.

How does your watch detect that something is wrong?

Smartwatches and smart rings don't diagnose diseases, but they do constantly monitor subtle changes in your vital signs that are imperceptible to you. When the body begins to fight an infection, it triggers an immune response that alters these parameters.

The key indicators your device tracks are:

* Resting Heart Rate (RHR): An unusual increase may indicate that your body is fighting something.

* Heart Rate Variability (HRV): This is the variation in the time between each heartbeat. A low HRV is a sign of physiological stress, whether from intense exercise, mental stress, or an incipient illness.

* Skin Temperature: A slight increase may be the first sign of fever, even before you feel it.

* Respiratory Rate: An increase may indicate respiratory problems associated with infections.

* Blood Oxygen Levels (SpO2): A drop can be a sign of severe breathing problems.

"Our study underscores the revolutionary potential of smartwatches for managing seasonal diseases and altering the course of future pandemics," concludes a study published in PNAS Nexus on the impact of early detection using wearables.

The astonishing accuracy of detecting COVID-19 and heart problems

The scientific evidence is increasingly solid. A meta-analysis from the University of South Australia, which reviewed 28 studies with 1.2 million participants, yielded compelling results:

* COVID-19 Detection: Wearables were able to correctly identify COVID-19 status (positive or negative) in 88 out of 100 people, an accuracy similar to rapid antigen tests. A 2020 study using Oura rings detected asymptomatic COVID through skin temperature.

* Atrial Fibrillation (AF) Screening: Identified AF, an arrhythmia that can cause stroke, in 87 out of 100 people, with sensitivity and specificity comparable to standard medical tests.

* Flu Detection: Another study modeled a 90% accuracy for detecting influenza before the onset of symptoms.

Even for chronic inflammatory diseases, such as inflammatory bowel disease (IBD), a Mount Sinai study showed that wearables can predict flare-ups up to seven weeks before visible symptoms appear.

The future of health is on your wrist: What's next?

Technology isn't stopping. Companies like Apple, Garmin, and Oura are investing heavily in improving these capabilities. Oura has already launched a feature called "Symptom Radar" that alerts users to potential respiratory illnesses. Apple, for its part, plans to launch a "sick mode" by the end of 2025 and is researching glucose and blood pressure detection.

The real potential lies in large-scale prevention. Researchers estimate that if people self-isolated after an early warning from their watch, reducing their social contacts by 66–75%, the transmission of diseases like COVID-19 or influenza could decrease by 40–65%.

This technology is also revolutionizing clinical trials, enabling continuous and objective data collection, which could accelerate the development of new treatments.

Important: Experts warn that these devices are warning tools, not diagnostic tools. If your watch displays abnormal data, you should not self-diagnose, but rather consult a doctor.