Understanding Sleep Startle Reflex in Dogs (and How to Help Them)

“Let sleeping dogs lie,” they say, but why? The idea is that if you disturb something, you might make things worse. For our canine friends, waking them from deep sleep can lead to a larger reaction than you’d think, including snapping, growling, jumping, and barking.

So, it’s best not to disturb them if you can avoid it, but how much should you be concerned if your dog is exhibiting this behavior? Why does it happen, and what can you do about it? Read on to learn about the canine sleep-startle reflex, when it’s not a big deal, and when it’s something you should try to stop.

What is the sleep startle reflex in dogs?

The sleep startle reflex, aka sleep aggression, is an instinctive response that dogs cannot control. This reaction occurs when they wake up and immediately lash out, assuming that danger is present.

When a dog sleeps, they experience sleep cycles, just like us. REM (rapid eye movement) sleep is the phase of deep sleep when their brain sorts through information from the day. They also need this phase of sleep to feel well-rested upon waking up. The sleep startle reflex can be triggered if a sudden sound or touch wakes a dog during this phase of sleep, at which time they are not yet in conscious control of their reactions.

While many dogs get startled when suddenly woken, dogs with sleep aggression may attack perceived threats for a couple of seconds before processing their environment and realizing they’re safe. For this reason, it isn’t typical to see a dog’s aggression escalate upon waking. With sleep aggression, dogs instinctively attack what’s near only in the first second or so — before stopping suddenly when their conscious brain catches up to their instincts.

It is important to remember that a dog with a strong sleep-startle response is not in control of this reaction. This can look like jumping, crying, barking, snapping, biting, snarling, growling, whining, or other similar signs of distress or aggression.

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Causes of dog sleep aggression

A dog who has been previously given a reason to feel vulnerable while sleeping is more likely to experience sleep aggression. Those causes can include:

• Generalized anxiety disorder

• Living in a shelter

• Loss of a stable home

• Recent traumas

• Chronic pain

A sleep startle reflex is one of the hallmark signs of PTSD in dogs after a traumatizing event. It’s a symptom pet parents should look for if something happened to them, or when bringing a new dog into their home. 

Other causes of sleep aggression can include:

• Chronic lack of sleep

• Chronic inflammation (allergies, IBD)

• Medications affecting dog behavior (steroids, anti-anxiety, or depression meds)

• Uncomfortable sleep (temperature, bedding, lighting, housemate issues)

When should you go to the vet?

The most important reason to see a vet for sleep aggression is if the behavior is new. Even if you think you know the trigger, changes in behavior, especially those classified as potentially aggressive, should be checked out by a vet for everyone’s health and safety. 

If your dog has woken dramatically from sleep, and you’d like to get to the bottom of why — and make sure it’s not because of an unmet need or untreated problem — check in with your vet as well as your starting point.

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Is there a treatment for sleep startle reflex aggression in dogs?

Unfortunately, there is no single, effective treatment for sleep startle reflex aggression in dogs. If there is a known trigger or cause, sometimes treating the underlying issue can ease their response over time. 

For some dogs, the need to protect themselves upon waking is an ingrained instinct, and it may be better to focus on management of the behavior rather than treatment.

How to stop sleep aggression in dogs

The best thing to do is try to avoid an episode. Here are a few tips to help you prevent sleep aggression in dogs.

Speak gently

Find what works best for your dog. Saying their name quietly from a few feet away may work, as can saying other favorite words such as “treats,” “outside,” and “walk.” Just be careful not to use a word that triggers too strong a response, because this can be the same as a loud noise or touching them.

Change the lighting

Dogs sleep more deeply and for longer periods at night, just like us. Increasing the lighting where they’re sleeping can naturally cue their body to come out of REM sleep and wake up without stress.

Soft touch

For some dogs, touching them very gently or in a certain area can help avoid a startle response. Moving bedding around them, petting them gently with a soft object, or offering a favorite toy can sometimes help avoid startling them. Remember that for some dogs, any form of movement or touch can be alarming until they have a chance to process. So you may need to cue them with gentle words and soft lights before attempting any touch for better odds of success. 

Always practice ways to gently awaken your dog with touch, and seek help from a trainer or behaviorist if your dog’s startle response includes biting. 

Training

You can teach some dogs that touching a certain area of the body always equals a treat or their favorite toy. You should practice this while they’re awake: For example, a light pet on the shoulder is followed by something they like, in hopes that a similar touch, which wakes them up, replaces their sleep startle reflex with the expectation of a treat.

Don’t punish your dog for their response

Your dog is not in control of their body in that first second they wake up, so punishing them for what they do will not change the behavior. Since the source of sleep startle aggression is an instinctive response to feeling vulnerable during sleep, reinforcing the idea that something bad happens upon waking can make the problem worse or more frequent.

Don’t decondition with startling ways to wake them

Do not attempt to decondition this behavior without a trainer. If your dog gets startled by specific sounds or types of touch, you do not want to repeatedly wake them with that trigger. 

Managing the sleep startle reflex

Making sure your dog has plenty of time to sleep in an ideal sleeping location can ease their symptoms and keep everyone safe. Some steps to take include the following.

• Designating a safe, comfortable sleeping area where they won’t be woken by other pets, children, visitors, loud sounds, and so on.

• Make sure your dog’s bedding meets their orthopedic needs, especially in senior dogs with arthritis or other pain conditions.

• Treat the underlying cause, if known.

• Keep the sleeping area dark until you want your dog to wake.

• Maintain a routine with them.

• Feed them a nutritionally balanced diet.

• Establish a positive routine after your dog wakes, such as time outside, a quick treat, and petting them with a happy voice.

• Keep space between you and your dog if you need to wake them.

• Don’t allow pets or other people to wake your dog.

Commonly asked questions

Can dogs have sleep paralysis?

Sleep paralysis is not a documented condition in dogs. Although it may occur, it would be considered very rare. 

Why does my dog get aggressive at night?

Nighttime aggression in dogs can occur for many reasons. As dogs age, their eyesight after dark can weaken. They may feel stressed if they can’t sleep comfortably, or they may have unmet needs that we don’t know about. 

Is pacing a sign of pain in dogs?

Pacing can absolutely be a sign of pain in dogs. This is a common symptom in senior dogs with pronounced arthritis and is because flexing most of the leg joints to lie down hurts — so they often pace anxiously instead. It can also occur in dogs of any age with stomach pain. 

References

Naganuma, Fumito, et al. “Histamine N-Methyltransferase Regulates Aggression and the Sleep-Wake Cycle.” Scientific Reports, vol. 7, 21 Nov. 2017, p. 15899, www.ncbi.nlm.nih.gov/pmc/articles/PMC5698467, doi.org/10.1038/s41598-017-16019-8.

Pike, Amy L. “Sudden Onset of Fear & Panic in a Bernese Mountain Dog.” Clinician’s Brief, vol. 19, no. 1, 2021, pp. 83–87, www.cliniciansbrief.com/article/sudden-onset-fear-panic-bernese-mountain-dog. 

Wu, Ming-Fung, et al. “Lesions Producing REM Sleep without Atonia Disinhibit the Acoustic Startle Reflex without Affecting Prepulse Inhibition.” Brain Research, vol. 528, no. 2, Oct. 1990, pp. 330–334, doi.org/10.1016/0006-8993(90)91677-9.