how to stop/kill an app after some time?

[rEcEivEr]

I'm listening to some music when I go to sleep. But after I've fallen asleep, the app's still running until I wake up and kill it. Which means it's running a few hours, draining battery life.
I've been searching google for an app that could auto kill an app after a designated time, but no luck.
I don't want to stop the sound, but the app itself.
I don't know if it's even possible?

 

[Clementine_3]

https://market.android.com/details?...yLDEsImNoLnBib29zLmFuZHJvaWQuU2xlZXBUaW1lciJd
That is a really nice sleep timer, it works quite well. I used to use it before PowerAmp added an in-app sleep timer and never had an issue with it.