Your dog was flat out on the sofa. Somebody stroked them, or moved past their bed, and there was a growl. Perhaps a snap, with no contact. Everyone in the room went quiet.
Safety note
Get help now if there has been contact of any kind, if this has happened more than once, or if a child was involved. That needs a veterinarian and a qualified behaviour professional who can see your dog in person. Book the veterinary examination regardless, because sudden behaviour change warrants one and pain frequently presents as a change in behaviour rather than as obvious lameness. Do not punish the growl. It is the warning you want your dog to keep giving.
What is happening when a dog is woken
A dog deep in sleep who is touched has a fraction of a second to work out what is happening. What comes out is a startle response, not a decision about you.
Adolescent dogs are often short of sleep, and short sleep means more of it is deep sleep when they finally get it. A dog who is woken 6 times a day by a household is a dog with less margin.
None of this is about status or your dog testing you. Read the growl as a sentence: I did not know it was you, and I need a moment.
Why the growl gets kept, not corrected
Punishment-based approaches are associated with fear, avoidance and defensive aggression. A dog who learns that growling brings trouble can stop growling and go straight to the next thing.
The growl is the smoke alarm. You want it loud, early and reliable. Reward-based methods are what the veterinary behaviour guidance recommends for the work underneath it.
Change the household rules this week
Nobody touches a sleeping dog. Use your voice from 6 feet away and wait for your dog to lift their head and look at you.
Say the same 2 words every time you need them up, in an ordinary tone, then drop a piece of food on the floor away from the bed.
Give your dog a bed that is out of the traffic. Not in a doorway, not behind a chair where somebody has to step over them, not on the landing.
Make the sofa and your bed off limits while this is live, if your dog sleeps there. A dog asleep where people sit will keep being woken by accident.
Brief the children in one sentence they can remember: when the dog is asleep, the dog is out of the game.
Then teach that a voice means good news
When your dog is awake but resting, say their name from a distance and toss food. Do 5 a day for 2 weeks, and stop before they get up.
Never use the same words to move your dog off something they want. Waking and evicting have to stay separate, or the cue gets poisoned.
Work below the point at which your dog reacts. If a growl happens, you were closer, quicker or quieter than your dog could manage; add distance and slow down.
Keep a note of every incident with the time, the room and who was there. A behaviour professional can do more with 5 lines of that than with a description of the growl.
Start with the sleep itself
This behaviour clusters in dogs who are not getting enough undisturbed rest. Work out how much sleep your adolescent dog is actually getting before you decide anything else, because the number is usually the surprise.
Relaxation is also trained as a behaviour in its own right, in short repeatable sets below your dog's threshold. A dog who can settle on a mat in a quiet corner is a dog who is asleep in fewer places where people walk.
Handled this way, most households stop seeing it. We cannot promise that for any individual dog. That is why the veterinary check and the professional referral sit at the top of this article.
Today's version, in one line: move the bed out of the walkway tonight, and use your voice from across the room.