Like this: “Alexa, set a sleep timer for 30 minutes.”
It will respond with ‘Okay’ and repeat the amount of time for the timer.
How to Set a Sleep Timer on Lights to Fall Asleep
More easiness.

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It will respond with ‘Okay’ and repeat the amount of time for the requested timer.
After that time period elapses, the lights will turn off automatically.
If you haven’t yet automated your lighting, it’s simple toconnect your lights to Alexa.
How to Set a Sleep Timer for Audio and Lights Together
This is trickier.
You’ll need tocreate a routinefor this one to make multiple devices work together.
How to Cancel a Sleep Timer
Again, very easy.
Just tell Alexa to “Cancel sleep timer.”
It will remove the timer.