There currently is one option to travel by night train from Copenhagen (Denmark) to Bad Schandau (Germany), taking between approximately 10 and 11 hours: Namely the RJ 387. These lines are operated by DSB and Deutsche Bahn.
DSB, Denmark's national railway, runs passenger trains throughout the country and connecting services abroad.
Deutsche Bahn (DB) exited the actual night train business in 2016. However, it operates around a dozen Intercity and Eurocity trains that run exclusively at night.
These trains only have first and second class seats. The cars remain lit throughout the night and the seats cannot be reclined.