There currently are a variety of options to travel by night train from Copenhagen (Denmark) to Hamburg (Germany), taking between approximately 5 and 7 hours: Namely the RJ 387, the 301 and the 10301. 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.
In these night trains, there are only first and second class seats. The lights stay on all the time and there is no way to recline the seats.
Snälltåget offers night travel with various comfort levels on night trains between European cities.
Snälltåget provides three options: budget seats in open coaches, berths in shared compartments for up to six people, and private compartments for groups. All berths include pillows, sheets, blankets and duvets.
In shared and private compartments, seats convert to berths at night. Each compartment features three berths on each side with ladders to reach the upper berths. Private compartments are ideal for groups seeking more privacy.
Pets are only allowed in private compartments and must be registered during booking. Bicycles cannot be brought on the train, but folding bikes can be stored as hand luggage in the compartment or on luggage racks in the seating coach.