OS X El Capitan randomly wakes from sleep - Macbook Air

Hi,

I'm using a mid-2011 Macbook Air and since updating to OSX El Capitan it randomly wakes from sleep. This didn't happen at all with Yosemite.

Latest El Capitan update didn't solve this.

Any clues on what's going on? (BTW this happens regardless of the Macbook Air being connected to a TV or not, so that can't be the cause).

Thanks