Iphone 5 battery dies quickly?

So my iphone is like completely new, I easily noticed its battery is terrible these days. It was full at 11:30pm and then at 4:00am it went down to 29%.In addition, yesterday it took 3 hours to fully charge instead of 2.
here it says on my iphone: Usage: 4 hours, 10 minutes. Standby 7 hours, 42 minutes.
And even more, yesterday I was using it while the battery was close to 14% then it suddenly turned off needed to be charged.
Help!

I have the 5 as well. Close all your apps every time you get a chance! And also turn your brightness down. This well show good improvement.

I have also used the iphone5 which it really dries quickly. So i have download an app from the internet, but i have forgot its name, you can search on the Apple store, you may find easily