[header] How to handle a dog's nightmares [title] Decide whether to wake up your dog. [step] When your dog is having a nightmare, your first instinct may be to wake up your dog. However, this isn't always the best idea. 
Waking up your dog would disrupt its sleep cycle, causing it to feel confused and possibly lash out at you. It's often better to let a dog continue sleeping through the nightmare.