There currently are a variety of options to travel by night train from Hamburg (Germany) to Copenhagen (Denmark), taking between approximately 6 and 8 hours: Namely the RJ 386 and the 300. These lines are operated by DB and Snälltåget.
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.
Snälltåget offers night travel with various comfort levels on night trains between European cities.
Accommodation ranges from individual seats in coaches to shared compartments with up to six berths and private compartments for small groups. All beds include bedding and blankets.
Both shared and private compartments transform from day seating configuration to night bed mode. With three berths per side and ladder access to upper berths, private compartments offer the best option for groups.
Animals are permitted in private compartments only. Bikes are not allowed, but collapsible bicycles can be transported as hand luggage or stored on luggage racks.