[buzzdenver]

I do not have an answer for you, but I have a very low level of trust in the deep sleep numbers, as they are based on heart rate and not brain waves.

[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.