Create a "personal automation" on your iPhone that turns on Theater Mode when Bedtime starts. Create a second automation that turns Theater Mode off when you wake up. Make sure "Ask Before Running" and "Notify When Run" are unchecked. It works about 99% of the time, for me (sometimes the morning automation doesn't work correctly, for some reason. If you wanted to make it absolutely bulletproof, you could change it to simply turn off Theater Mode at a specific time, each day - that would probably be more reliable).
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