Hi! Welcome to the Samsung Members community!
In the Health app, you can change your sleep data to whatever you like. (Image with random time example) You can also set alarms for whenever you want. You can set schedules to your preferred times as well.
Unless you meant something else?
However, this is a Samsung Member-to-Member chat, so Samsung won't see this. If you want to contact Samsung, go to the Samsung Members app > Support > Feedback.