Apple Watch can act as reliable & accurate 

The ECG feature alongside other measurements in the Apple Watch can act a basic stress detector.

Apple Watch Series 6 was rumored to include features for monitoring mental health issues

Apple has not included such an anxiety or stress app as yet. 

New study claims that the Apple Watch is already useful for predicting stress 

They were instructed to collect data 6 times during the day in approximately three-hour intervals 

This is the first study to use Apple Watch ECG data to predict stress levels of individuals

While the current models have high specificity, predicting 'no stress' states relatively well 

It lacks the predictive power to accurately predict the 'stress' states as of yet.