Connecting to external display and sleeping

Let's say I'm using my MacBook while watching tv, but then I come into my room to connect to my external monitor. When connect to the external monitor, and to the charger, when I close the lid it still goes to sleep. Is there a way arond that while plugged in to the external display? Or does it automatically go to sleep ANY time when its closed?

You need to get and external mouse and keyboard to wake it up from sleep when it's closed.

Right, I have Apple bluetooth keyboard and mouse, but I don't want it to go to sleep when I shut the lid after plugging it in to the monitor and charger.