Sleep timer

So my idea is to install a outlet time to my tube pre amp and tube and to kill the power if I fall asleep while listening to music so I can save the life of my tubes. Is this common? Does anyone have any suggestions on the proper way to achieve this? I know it has to be a thing?
Relax. Nothing can save the life of your tubes. They will die. Trust me.

I'd rather not fall asleep leaving my amp on though.
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If you are prone to falling asleep while listening to music, simply program a wake up call on your smart phone. 
@testpilot I'm to lazy to get up and walk to the amp and turn it off though...
Nest type remote outlet or some such device from your phone?