There currently are a variety of options to travel by night train from Augsburg (Germany) to Bremen (Germany), taking between approximately 8 and 10 hours: Namely the NOX 1790 and the ICE 618. These lines are operated by Nox and Deutsche Bahn.
Nox is a new night train between Hamburg and Munich with stops in Bremen and Augsburg. It runs three times a week in each direction from 23 March 2027.
There is only one category: the Nox Suite, a reclining seat with privacy wings in an open-plan car, with a reading lamp and a small table.
You can book the Basic fare, which can be changed or cancelled for a fee, or the Flex fare, with free changes and cancellation until 3 hours before departure.
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.