Sputnik Sweetheart discussion

Why did Sumire go into that strange state where she was sweating, crouching in Miu's room, biting something, and almost catatonic before making her move on Miu? She mentioned something to the effect of: "this happens to me sometimes".

I've been at a loss to explain why this happened. Does anyone have any ideas?

There's a few reasons that come up in my mind when I think of that scene.

It's likely because of trauma.
Naoko in Norwegian wood by Murakami (a mentally unstable character) was also prone to similar catatonic behaviour.
Do you remember when "K" is reading through the documents Sumire wrote on the floppy disks she left behind? She wrote about a re-occurring dream in which she pictures her biological mother trying to say something to her, but Sumire can't make it out before she disappears into darkness. This is immensely tormenting for Sumire.
This is exasperated by the fact that she has more nightmares due to her stopping her smoking addiction cold turkey (she states this in passing as the cause of some of her impromptu midnight calls)

Another contributing factor may be Sumire's intense desire to be with Miu, and her hesitation to do so out of fear that Miu may not reciprocate (which she doesn't, and Sumire responds drastically by disappearing)