[Venu 3] Manually control Do Not Disturb and Sleep Mode

So I set sleep and wake window times for my Venu 3. In the evening when my sleeptime arrived it will automatically enable Do Not Disturb and Sleep Mode.
The next morning after my wake time it wil automatically disable Do Not Disturb and Sleep Mode.

However, sometimes I know I will be sleeping longer then my standard wake time and I want to be able to manually enable Do Not Disturb and Sleep Mode and NOT have Garmin automatically disable them too early with the risk of being woken up because of alerts et cetera.
How can this be achieved when:
1. Garmin already automatically enabled Do Not Disturb and Sleep Mode
2. Garmin didn't already automatically enable Do Not Disturb and Sleep Mode

Thanks for the help.