Regional day ticket for Bavaria:

Travel on a day of your choice from 9:00 am to 3:00 am the following day
On weekends, public holidays (including Assumption Day) and on 24 and 31 December from midnight to 3 am the following day
 

Regional night ticket for Bavaria:

Sunday to Thursday from 6 pm of the specified day of validity until 6 am the following day
Friday, Saturday and 15 August (Assumption Day), 24 and 31 December from 6 pm on the specified day of validity until 7 am the following day
On the night before a public holiday during the week that is observed throughout Bavaria from 6 pm on the specified day of validity until 7 am the following day