On macOS, you can toggle Do Not Disturb from the notification bar so bring up the bar by clicking on the icon in the menubar.
Now swipe down with two fingers and you'll see the option to turn on Do Not Disturb. Switch this on and the Mac won't make any notification noises or show any alerts on the screen until you either turn it off or until the next day.
To activate Quiet Hours on Windows 10, simply click on the notification icon at the end of the task bar.
You'll now have access to several different options, click on Quiet Hours to switch on Do Not Disturb. When you want to turn it off, simply click on the icon again.
On iOS, just swipe up from the bottom of the screen to bring up Control Centre.
Once you have Control Centre up, just tap on Do No Disturb to switch it on.
To switch on Do Not Disturb on Android, just swipe down from the top of the screen.
Then tap on Do Not Disturb.
You can now choose how long Do Not Disturb is on for, when you've chosen your options, tap on done.