Sometimes at night I can't get back to sleep after waking up. I then get up to do small things. This period of standing can last between 10 and 30 minutes.
For example, last night I went to bed at 10:50 p.m. and got up for 15 minutes at 12:30 a.m., then went back to bed at 12:45 a.m. and slept until 5 a.m. So my night was split into two parts.
The problem with my Vivoactive 5's sleep recording is that the watch completely ignores my first part. It considers my night to start around 1:15 a.m. even though I had deep sleep from 11 p.m.
And this is systematic, as soon as a night is split into 2 parts the 1st part is ignored and does not appear anywhere in the sleep data. This obviously distorts the results of the sleep.