I have been using Apple Watch Series 8’s sleep stages feature since the day I bought it. But it always showed me multiple awakenings although never remembering I woke up that much on those nights. Last night to test sleep stages I wore my Series 8 on my left wrist, and my brother’s Series 5 on my right wrist(I am right-handed.). Again I don’t remember I woke up last night but my Series 8 thinks I woke up more than 5 times. Although the sleep stages are so similar between Watches I think there is a problem with Sleep Stages on Apple Watch Series 8. Although I adjusted the bands at the same size, Series 8 was a bit looser on my wrist. It can be a cause of this. And as you know Series 8 has much more sensitive accelerometer and gyroscope than Series 5. I think this sensitivity might cause this problem as well.
Uyanık is Awake in Turkish.
Yüzeyel is Core.
Derin is Deep.