Question about Huawei Band 4e

I just used this watch for 10 nights. No alarms linked to the sleep phases (but I don't remember well ...). It was for a long time !
I just know that you have to install the Huawei app store, then get the app. You can get a graph with your sleep phase. But
I tested two watches (low price - one at each arm) during some nights and obtained each night different graphs from the watches. I think that not an useful product !
Best regards