[mattgreenrocks]

FWIW, my Apple Watch's reports of deep sleep line up with my Zeo (EEG)'s numbers from awhile ago.

[inerte]

This guy over here https://youtu.be/BQMIAkt4P48?si=XQY6jLLKFpS4wkzv is always testing fitness / sleep devices and he compares to better machines that are known to more precise. The latest Apple Watches do pretty well overall.