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?
gguy767
If you are prone to falling asleep while listening to music, simply program a wake up call on your smart phone.