iPhone wont go to stand by mode on its own.

I am using iPhone 4s with iOS 7. Soon after updating the software i noticed that notification center wont come down by sliding from the top of the screen, same happened with the control center. Moreover, the phone wont go into stand by mode on its own, i have have to push sleep/wake button to turn off the screen. And for some reason this made batteries drain faster than they should.The only solution to the problem i found is to restart the phone but the problem occers once in a while. Does anyone know why is this happening or any permamnet solution to the problem.