Wow. This is really fascinating. Based on that article, it seems as if I spend quite a bit of time in some state of a shutdown. Usually when I'm tired (for various reasons other than and including lack of sleep) I have some sort of "meaning blindness." I don't know how many times I'll be talking to someone, and I'll hear what they say, but I won't understand it until 5 or 10 seconds later. This is true even if it's something simple, like "I'm going to the store, I'll be back in an hour." It's true for visual things too. I have frequently not noticed (and thus reacted to) things that I should have, even though I was staring right at what it was that was happening.
Although I really wouldn't consider this a "shutdown." The word shutdown implies that the mind stops functioning altogether. This is definitely not true. Usually when this sort of stuff happens, it's because I'm in a state of hyperfocus, thinking about something else. Although when this happens, usually what I'm thinking about is something I'm stressed out about, or I'm intentionally trying to block out sensory inputs due to some sort of overload. Although, I suppose that is what is considered a shutdown. I'm sorry if it seems like I'm just thinking in circles right now, it's almost 4:30AM, I'm probably in some sort of half-shutdown right now.
But, while on the same subject, I don't believe I've ever had a full shutdown. I know for a fact that I've never had a motor shutdown, and while sometimes my speech and language can be somewhat impaired, I don't think I've ever totally lost that ability. Usually what happens is that I lose my ability to regulate my tone of voice, so that when I talk not only am I blunt and rude, but I can no longer cover up an irritable tone. A good example of this is when I tell my mom, "I'm tired of listening to you; shut up now." Although this might be considered more meltdown-like behavior. Maybe there are more similarities than I originally thought.
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Remember, all atrocities begin in a sensible place.