OK, you do have a Merlin Magix system, which is good, you can have Automatic Night Service, based on time of day, and day of week.
The programming is done from a 4424LD+ telephone, or perhaps an MLX-20L, or through WinSPM software.
If you have none of the above in your system, you're going to need professional help to get it going.
Otherwise, you would go to Menu > SysProgram > Start > NightSrvc > Start
Here you enter the Day (0-6 where 0=Sunday, 6=Saturday), the starting Hour (2-digits in 24-hour format) and the Minute, then press Enter
Do this for each day that you want Night Service to automatically start.
Then back up and select Stop, do the same for when it will stop.
Finally back up, and select Time Control, select On, and Enter.