My computer sleep automatically even if Im still using it

Hello experts,
I am getting this very annoying issue on my computer. It automatically sleep even if I am using it. When it's on again, it will just sleep again. This started when I opened Google Chrome to check on my Facebook while playing some videos in YouTube. This computer was new and yet this issue happened for two times now. I am running Windows 8 on my ASUS G10AC-ID003S. I don’t know how to resolve this. Please help me.
