There currently are a variety of options to travel by night train from Bremen to Düsseldorf, taking approximately 3 hours: Namely the ICE 619, and the ICE 921. These lines are operated by DB.
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.
For the next 7 dates with connections, the cheapest offer starts at 16 EUR. Check our connection pages below for all availabilities!