1. In this literature review, heart rate variability measurements were able to detect mild mental stress, despite some gaps in data.

2. Furthermore, accelerometer-based sleep monitoring had a high accuracy and sensitivity in detecting sleep.

Evidence Rating Level: 2 (Good)

The Apple Watch has continually advanced the capabilities of smartwatches and are now able to gather various physiological parameters such as heart rate, respiration rate, and rhythm detection. Currently, their application to mental health monitoring and diagnosis is unknown. As a result, the objective of the present study was to identify current and potential physiological monitoring capabilities of the Apple Watch, relevant to mental health monitoring. Furthermore, this study sought to examine the accuracy and validation status of these measures and their implications for mental health treatment.

Of 5583 identified records from both published and gray literature, 19 were included in the analysis from 2015 to July 2021. Studies were included if they used the Apple Watch for either physiological data validation or psychology of mental health studies. Particular monitoring data points included sleep tracking, heart rate monitoring, respiratory monitoring, and energy expenditure. Data synthesis was performed using Clarivate analytics in EndNote.

Results demonstrated that the Apple Watch performed reasonably well at measuring heart rate, heart rate variability, and step counting. Furthermore, heart rate variability was able to detect mild mental stress. However, atrial fibrillation detection showed mixed results and no studies recorded validation of the Sleep app feature. Despite these results, the present study was limited by the lack of a risk of bias assessment for the studies. Nonetheless, this study demonstrated that more objective measures obtained passively may aid in assisting clinicians in monitoring mental health disorders.

Click to read the study in JMIR Mental Health

Image: PD

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