After turning off Android phone screen, screen turns itself back on after a minute or so

Hello, forgive me if this has been asked before. I honestly couldn't find any answer.

I have my game running on my android phone, working wonderfully. The only problem is that if I was just playing the game and I turned the screen off eventually (maybe a minute) the screen will turn itself back on.

Basically:

• Play game.

• While game is still running I hit the sleep button on phone, screen turns off.

• A little while later, phone comes to life on its own, game is running where I left off.

Not sure id I'm explaining correctly. Any assistance would be much appreciated!