Now from the MUI files, uncovered by Windows Phone Lovers, we can learn a bit more about how it works.
The feature is similar the Do Not Disturb feature on iOS where you can set your phone to not notify you of call or text messages during certain hours.
The feature works together with the new Inner Circle feature, where you can add up to 40 contacts to the group, who will then be allowed to call you even when Do Not Disturb is active.
The new feature is another which will help bring parity between Windows Phone and other mobile operating systems.
See more of our Windows Phone 8.1 coverage here.