Make OS X El Capitan announce time only when screen is unlocked or during night time I use the incredibly useful feature on OS X to announce time on the hour for my time management by checking the option in Date &amp; Time preferences.



However, the time announcements keep going on during the night unless I shutdown my iMac (which I don't want to). Is there a way to silence it during night time or to make it not announce time when the screen is locked? 

I know there was a related question for OS X Lion but posting this to see if there is a better/different solution for El Capitan.
Do you have 'Do Not Distrub' mode set on?
Go to System Preferences -> Notifications and set up as needed.