Sound not coming from my Windows 8 Lenovo Ideapad P400 Touch unless I put it to sleep?

So, when I boot my laptop, the sound is initially working fine. However, if I leave it for too long, usually a few minutes, without ANY sound playing from it, the sound will just plain not work. I've tried muting it and un-muting it and checking to see if the speakers are working properly and according to the laptop they are. However, if I put it to sleep and then re-open it, the sound is working perfectly fine unless I leave it for too long again without playing any sound. Any suggestions?