There currently is one option to travel by night train from Padborg (Denmark) to Nässjö (Sweden), taking approximately 6 hours: Namely the EN 344 operated by RDC.
RDC Deutschland operates the RDC Euronight night train between Berlin and Stockholm three times a week, with stops in Hamburg, Copenhagen and several Swedish cities along the way.
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.
The couchette car has compartments for up to six people, bookable as a private compartment or as individual berths. Each berth includes a pillow, sheet, and blanket. Seats convert into berths for the night. Washrooms and toilets are available in the car.
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.
Breakfast is included for passengers in both 1st class and 2nd class sleeper compartments and is served directly to the compartment. Travellers in couchette and seating cars do not receive breakfast.