Sleep phases accuracy devices comparison

I tested several devices wearing them on the same hand during the night and got different sleep tracking results. In particular in sleep phases detection. The movement diagrams are almost the same, but deep sleep in % is significantly different.
Please take a look at the screenshots: Garmin VivoSmart 4, TicWatch Pro 3 Ultra and Xiaomi Mi Band 7

Could you commend on this why is this happening and what is the best device to receive most accurate sleep phases tracking?


how did you do this? did you use multiple phones?

Yes, multiple phones

Hi, sorry for late reply…
The analysis is always the same, so if the results are different, then the data sets are different. I don’t have logs for these graphs, but just from the screenshots, the actigraphy at the top is not the same. They are close, but definitely not the same.
Also, the SpO2 data graph looks completely different, and the middle graph shows really different progress of HR values.
Did you wear all three wearables on the same hand (and on the same section of the hand)?

Yes, on the same hand and on the same section of the hand

Are the wearables provide different data consistently? Even the HR values are quite different.
I don’t have the logs, so I cannot tell how much different movement data the app had.

@lenka-urbandroid Is there a way to enable logs for movement & HR data in SAA app? Or export already recorded sleep data to file?

Hi, the logs are generated only on demand. Depending on how many events were happening, there is about 1-2 data history with tracking, and up to 10 days if you only use alarms.
In the Left ≡ menu > (?) Support > Report a bug, the app generates a set of files - one is debugging log, and 1-3 activity data.

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@lenka-urbandroid do you know if SAA sleep phase detection algorithm can be used for ring wearables? Because during the sleep you have different intensity movements on the finger (when you wear a ring) and on the wrist (when you wear smartwatch). Could you comment on this? Here is the sleep tracking result for the same night on the same hand, but O2Ring result is for the finger and Garmin result is for the smartwatch on the wrist. Which of this wearables has better accuracy in theory? On the finger or on the wrist?