We've set up notifications so they honour the "Do Not Disturb" setting on your phone. You can turn your phone to "Do Not Disturb" to occur at any time of the day you wish, such as while you're sleeping. To turn this on when you require it, go to the control centre - depending on the phone you have, you either swipe from the bottom or from the top right downwards, and look for the moon icon.
Tap it to turn it on, and then when you want notifications back, turn it back off again. If you use the alarm feature in the Clock app it will still alert you when notifications are switched to "Do Not Disturb". This feature is for all apps, not just Quin.