There currently is one option to travel by night train from Padborg (Denmark) to Norrköping (Sweden), taking approximately 8 hours: Namely the EN 344 operated by RDC.
RDC Euronight is a night train operated by RDC Deutschland connecting Berlin with Stockholm via Hamburg and Copenhagen, running three times a week in each direction.
Two sleeping car categories are available on board. The 1st class sleeper offers private compartments for up to three people with a private bathroom including shower and toilet; breakfast is included. The 2nd class sleeper has two-person compartments with a private washbasin and corridor toilets. These can be reserved privately or shared with other passengers in mixed or women-only compartments.
Couchette compartments accommodate up to six people and can be booked privately or as individual berths. All berths come with a pillow, sheet, and blanket. Washrooms and toilets are available in the carriage.
As the most economical choice, the seating car offers compartments for up to six people and open-plan seating. Each seat comes with a power socket and an included reservation. Toilets can be found in the vestibules at the end of the car.
Passengers in sleeping car compartments — both 1st and 2nd class — receive breakfast delivered to their compartment. Couchette and seating car passengers are not provided with breakfast.