Nightmare Academy by Dean Lorey
Charlie Benjamin is a lot like other little kids. He wants to have friends and have fun. He loves his family. Sometimes he has has bad dreams at night. However, when Charlie has a nightmare, he doesn't just wake up scared. Charlie's nightmares open a portal to the nether, a place full of monsters that would like nothing more than to maim and terrorize humanity. Thankfully, there is the nightmare division, a secret organization charged with controlling and removing these monsters once they cross over. It is the job of the nightmare academy to train and prepare those who work in the nightmare division. But can Charlie learn to control his power before he releases a creature too powerful to stop?