About sleep monitoring for apple watch

I recently bought the apple watch ultra2 and wanted to use it to check my sleep status. After I got it, I slept for more than 3 hours every day for 3 consecutive days, and the displayed bed time was also more than 3 hours. I always slept from 1 o'clock to 2 o'clock. I went to bed between and got up at 8:30, which is too much difference (I turned on sleep mode). What's outrageous is that there is no standing every day in the fitness ring. When I get up in the morning, I have stood up five times today, 😂 When I didn't have a watch before, I set the goal of 100 calories for the fitness ring. Because I was sedentary every day, I might not be able to finish the previous day's shift, or just finish it. After buying a watch recently, I took a taxi to the company in the morning and popped up saying that I had completed today's goal, and I consumed 400 calories after get off work.