DayZ | How to change Nighttime.

You can add this nighttime acceleration script to your server config "Text Editor".
Please check below the format.

serverTime = "SystemTime"; // Initial in-game time of the server. "SystemTime" means the local time of the machine. Another possibility is to set the time to some value in "YYYY/MM/DD/HH/MM" format, f.e. "2015/4/8/17/23".

serverTimeAcceleration=2; // Accelerated Time (value 0-24)// This is a time multiplier for in-game time. In this case, the time would move 24 times faster than normal, so an entire day would pass in one hour.

serverNightTimeAcceleration=20; // Accelerated Nigh Time - The numerical value is a multiplier (0.1-64) and also multiplied by serverTimeAcceleration value.

serverTimePersistent=1; // Persistent Time (value 0-1)// The actual server time is saved to storage, so when active, the next server start will use the saved time value.

You can copy this: serverNightTimeAcceleration=20; // Accelerated Nigh Time - The numerical value is a multiplier (0.1-64) and also multiplied by serverTimeAcceleration value.

NOTE: Please make sure there are no spaces between the scripts like what you have seen on your server config.