There currently is one option to travel by night train from Trzebinia (Poland) to Rzepin (Poland), taking between approximately 7 and 8 hours: Namely the EC 430. These lines are operated by Deutsche Bahn and PKP Intercity.
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.
PKP Intercity is Poland's national long-distance railway operator, running domestic and international train services throughout Poland and to neighboring countries.