Not really only in Germany. For instance Nordea Denmark closes its online bank between 2 am and 5 am. Probably because they don't have staff at those times to prevent scammers from transferring money out and people rarely need to use banking during those hours.
As someone who sleeps weirdly it has annoyed me once or twice, though.
As someone who sleeps weirdly it has annoyed me once or twice, though.