There currently is one option to travel by night train from Offenburg to Wittenberg, taking approximately 8 hours: Namely the IC 60409 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 40 EUR. Check our connection pages below for all availabilities!