Why Is My Dog Aggressive When Woken Suddenly?

Mary Simpson
by Mary Simpson
No one likes getting woken up suddenly from a deep slumber – but some dogs get aggressive in this situation. How do you wake your dog up safely?

We’ve all been entertained by the antics of our pooches as they sleep. From yipping, to twitching, to full-on leg action – its clear their dreamworld is pretty active and includes lots of running, playing, and chasing. Now, for the most part, our little buddies tend to float in and out of sleep; rousing when they hear something of interest – such as a fridge door opening or a food wrapper crinkling – then falling back to sleep again.

But not all dogs are this placid. Some react quite aggressively when suddenly wakened. It’s called a “startle response” and while it’s a survival instinct that has them ready to fight off that predator looming over them, it’s a challenge when its just you, your kids, or other pets that happen to be at the receiving end. While its not common with most dogs, for some its simply how they roll and it can result in aggression that includes growling, snapping, and even biting.

But why do some dogs resort to aggression over the more typical, easy-going response exhibited by most pooches? Well, lets look at how dogs sleep.

You may (or may not) be surprised to learn that dogs sleep between 12 and 14 hours a day. Its typically short naps scattered through the day with their longer sleep period occurring at night. Periodically, you will see your dog wake, lift his head, and look around. What he’s doing is a visual spot-check of the environment to assess potential dangers. So, on average he’s never really off-duty, he’s partially tuned-in. But dogs achieve a state of REM much faster than humans, so when he finally crashes, he does so deeply. Is this what explains why an otherwise loving and sociable pooch can be so suddenly startled and strike as if in fear for his life?

The answer is yes, and no. In fact, there are a number of reasons, that include:

  1. Confusion: Being suddenly awakened from a dream, and not having the chance to regain his bearings.
  2. Fear: Being startled by an unfamiliar noise that immediately kicks him into a fight or flight mode.
  3. Exhaustion: Being newly adopted/rescued and over-tired because sleep patterns are out of whack.
  4. Resource-guarding: Feeling the need to protect his personal sleep space from a sudden, unexpected intruder.
  5. Stress: Living on-edge, and losing much-needed REM to wanting to stay on guard at all times.
  6. Medical: An undiagnosed health condition or injury may be causing him pain and result in aggression when touched.
  7. Sensory Loss: Loss of hearing can be distressing for a previously hearing pet, and cause even a light touch to startle him and instill fear.


Whatever is causing your dog’s aggressive startle response, it’s not something that you can train out of him – you have to learn to manage it. And here are some tips that can help:

  • Never scold him for snapping. It’s an involuntary reaction on his part, is not behavioral, and you don’t want him to stress about napping or associate it with a negative experience when he wakes.
  • When you need to wake your dog, find a way to do so in a manner that won’t startle him. Softly call his name, leave a treat near his nose, crinkle some food wrappers – all will gently rouse him with that unexpected, jarring factor.
  • Keep his sleep space away from high-traffic areas, and make it a no-go zone for kids and visitors. Explain to friends and family why its important they respect his need to feel secure and then enforce it.
  • When you’re out with friends – camping, on a picnic, a car ride… and you know it’s likely he’ll doze off, consider a muzzle. It’s not an ideal, but it allows him to be alongside others without the fear factor of what happens if he’s suddenly wakened.
  • Re-condition his reaction to being woken by providing him with a treat. Make sure its only doled out when no snapping occurs, but it will help condition him into feeling anticipatory of food things versus negativity. While you can’t fully train this instinct out of him, you can temper it.
Mary Simpson
Mary Simpson

Sharing space with three seriously judgy Schnoodles and a feline who prefers to be left alone. #LivingMyBestLife

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