Allistic parents will tend to have trouble fully understanding what is happening to an autistic child during a meltdown, especially since it is an emotionally fraught event for all concerned.
Since I have been experiencing meltdowns for over seventy years now, I thought it might be useful to offer some personal perspective. Autistics tend to be profoundly different from one another, and my experiences may differ in some respects from your child’s (or yours, if you are autistic — I’d be interested in hearing your experience).
To begin, as is often pointed out, a meltdown is not a tantrum. A tantrum is a behavioral device intended to influence others, to gain some objective. A tantrum is something you do to achieve an effect. When you get what you want, you stop acting out. Despite being distinct, a tantrum and a meltdown may occur more or less together, with one feeding the other.
A meltdown is not something you do, it is something that happens to you. For me there may be a brief moment of fun during the screaming and physical destruction, but overall it’s “Not THIS again! Somebody make it stop!” I am also a migrainer, and seeing the onset of a meltdown is similar in some ways to detecting the pre-migraine aura.
A meltdown is a process, part of the way a complex control system behaves when it bumps into conditions that can cause runaway feedback that can be highly destructive. For a physical example of such a system, do an engine search for “Tacoma Narrows Bridge Disaster“. Many is the time when I have felt like the bridge itself, not those who got dumped into Puget Sound.
Meltdowns can be triggered by a wide variety of stimuli. My childhood friend Donnie was unable to handle the sensory onslaught of a visit to the barber shop. His reaction to attempts to enroll him in elementary school eventually led to his disappearance into the Colorado State Home For Feeble-Minded And Spastic Children. What usually gets me is frustration, especially if I am already stressed. In rare circumstances I can become dangerously violent, although so far it’s been a few cases of property damage, with assault on another person not having happened, mercifully. EDIT: Except for that bully I accidentally beat up in the ninth grade, after he triggered a meltdown. That did sort of put a halt to the bullying for some time.
Meltdowns are different for me now that I’m in my seventies, compared to what they were like when I was six. The primary difference, in my current estimation, is that I now know that I am autistic, and what a meltdown is, and ways to be aware that one is on the way, and ways to stop it from passing the no-return threshold, if at all possible.
The inception of a meltdown reminds me of one of those playground slides that starts off with a gentle slope, then suddenly bends downward steeply — if you got this far, you have no choice about going farther.
The aftermath of a meltdown, depending upon its origin and severity, resembles a hangover, the unpleasant trailing experience of a migraine or some other post-cataclysmic period of recovery. Remorse and/or a depressive episode may follow.
To those inclined to look at meltdowns as episodes of deplorable self-indulgence, I recommend paying closer attention to the ordeal from the standpoint of the human going through the wringer.