Yes buddy.it is happening to me also.i have Lumia 520.same battery capacity.I think u r using win 8.1 dev. preview. It will be solved in win 8.1 official version.
But the point is battery should not drain that much in the first place and that too on standby.Just switch wifi and cellular data off.bcoz I will drain your battery at the rate of 3% every hour.don't switch wifi and cellular data on while u sleep at night.ur battery life will improve.
Make sure that you don't have 1000 background tasks on.
Make sure that you don't have 1000 background tasks on.