Hi.  There will be something in your setup external to Sonos that is causing this.  Sonos products are just not going to do this unprompted.  Do you have any other control systems in your home, e.g. Alexa, Homekit? 

That suggests that the cable box you have the sound bar (either one) is connected to is waking up, probably  in order to check for software updates. 

Connect the Arc to your TV, instead of the cable box, and make sure the TV’s software is up to date. Or check with the maker of the cable box to see why it is powering the output while it checks for new data. 

Good thought Bruce.  

@Yogibear . I also wonder if you have Autoplay enabled on the Arc and what would happen if you disabled it?

Thank gentleman, I think my first order of business is I will unplug the google assistant and Alexa tonight , to rule out that avenue. Looked to turn off auto play on the Sonos app and could not find it

Autoplay - in the Arc settings, under Home Theatre, disable TV Autoplay.

Thanks so much John, turned of ungroup on auto play and auto play  and as I said I will unplug google assistant and Alexa tonight so well narrow from there. Again thank you

No worries.  Please post back with how it goes.  I am totally confident there will be a resolution to this problem, even if we don’t solve it tonight.