I downloaded the sleep as android data (sleep-export.csv) and noticed that sometimes different sleep phases overlap.
E.g. Light start is at 3 AM, then REM Start is at 3:15 AM, then REM End is at 3:25, and then Light End at 3:30 AM.
This is also the case for other sleep phases.
How is this possible? Is this an error or is there another explanation for this?