Export sleep data from S-Health
It's not so convenient to do on a daily basis but you can export all your data from Samsung galaxy health. 


In the top right corner click on the three dots
Choose settings
In the "Data" section choose "Download Personal data"
Click "Download" at the bottom of the screen
Verify your Samsung account password


It will download a bunch of csv files to My Files > Internal Storage > Samsung Health > Download > Samsunghealth_[your username]_[download date and time stamp].

One of them will be "com.samsung.health.sleep.[download date and time stamp].csv

Some of the information is useful, some is not.