Sleep Startle in Dogs (Is My Dog OK?)

Written by Anna Hollisey

UpdatedNov 15, 2023

“Sleep Startle” happens in the moment when your dog is awoken from deep sleep. They’ll sometimes behave in an unusual way, growling or nipping – because their internal alarm has been triggered and they’re taking precautions. This is an involuntary reaction and in itself, does not mean they’re being aggressive.

How Do Dogs Sleep?

It’s believed that dogs sleep in the same pattern as humans. First there’s a lighter type of sleep (SWS), and then there’s deep (REM) sleep. These alternate in a pattern.

If your dog is dreaming – even if it seems to be a nightmare – then you shouldn’t wake them, tempting as it seems. This is the deepest phase of sleep and it’s when they’re most likely to exhibit ‘sleep startle’.

What Causes ‘Sleep Startle’?

‘Sleep startle’ is the brain triggering your dog’s ‘fight or flight’ response mode, which releases adrenaline. It can cause aggressive (and unusual) behavior. Although any dog can suffer from ‘sleep startle’, it’s more likely to happen when they are feeling stressed or nervous.

Rescue dogs often display ‘sleep startle’. If they were raised in kennels, they were accustomed to sleeping alone, and might take a while to get used to a busy household. If they suffered ill treatment then they will wake up on high alert, because they must be ready to deal with an attack or problem.

In other words, if they were not raised in a secure and safe environment, they’re quick to return to a state of anxious alertness.

Whilst any breed can exhibit sleep startle, it’s especially prevalent in ex-racing greyhounds. Not only are they usually raised in kennels, but they’re not used to sleeping near humans.

FOTP’s Kim says:

“When we first brought our ex-racing greyhound/learn/dog-diaries/what-ive-learned-after-adopting-an-ex-racing-greyhound Elodie home, she soon adapted to the finer comforts in life. To this day, she calls dibs on any piece of furniture and takes great umbrage at being told she can’t sleep on the bed. We learnt quickly that if she slept on the bed, and we rolled over or fidgeted in our sleep, it could wake her up. Every now and then, she’d sleep startle. She’s never snapped at us when she’s been awake but she did nip us a few times in the night. It became easier for her (and safer for us) to make her sleep on her own bed but we’re still careful about waking her up when she’s fallen asleep on us in the evening.”

Preventing Sleep Startle

Firstly, it’s important to respect your dog’s sleep time. It’s essential for them to have rest, recharge their immune and digestive systems, and maintain their circadian rhythm. This means that you should let them build a routine and try to avoid waking them at unexpected times.

During the day it can be more difficult to let sleeping dogs lie – especially if they pick an awkward spot to sprawl! If you need to wake or move your dog, make sounds (or say their name) and approach gradually. Give them several moments to rouse themselves before you’re right in their face. If they don’t wake up quickly, don’t force them.

It’s important to explain this to other members of your household – especially young children – too.

If sleep startle is becoming a problem, try:

Moving your dog’s bed to a quieter place or another room, where they can remain uninterrupted. They’re likely to nap during the day, while people are around, so giving them a quiet space can help.
Teaching children that they should only give the dog attention when the dog comes to them. They should not be in the habit of approaching, hugging, or smothering the dog.
A crate can be useful because it provides the dog with a sense of security, but also prevents them from doing harm to anyone who startles them. It’s wise to introduce a crate gradually and without pressure.

How Do Dogs Sleep?

What Causes ‘Sleep Startle’?

Preventing Sleep Startle

Further Reading