Does Karkat have insomia now, or was that always a thing? If the demon thing eat the troll’s dream planet, is Karkat teleported there everytimes he sleeps.
Basically, is he unable to sleep because he no longer has a dream body to go to, because he has to focus so hard on surviving that he is willing himself awake, or because is dream body is still valid but trapped inside the demon swirl so Karkat is forced to stay in there and see horrible shit.
There is more to this sleep thing than just basic sleep.