I have a Vivoactive and the latest Connect Mobile for Android running on a Samsung Note 2 but can't find a way to block notifications at night. Blocking mode on the phone or setting to silent has no effect and setting the sleep time in the App has no effect.
On the Pebble watch you can set a "do not disturb" time directly at the watch. Why do we not have this facility? I do suspect this is a Android issue andossibly phone dependant as I can find any mention of this fault by others.