Dogs can’t tell you when they’ve had enough. There’s no warning bell. Instead it shows up in behaviour, and a lot of owners miss it until things boil over, whether that’s a snap, a meltdown, or a dog that just won’t settle no matter what you try.
Overstimulation happens when a dog’s taking in more sensory input or excitement than it can actually handle. It’s not misbehaviour, even though it can look that way. Catching it early is the best way of managing it properly.