Makes me think of Vernor Vinge's "Deep" novels -- idea there was physics changes depending on your distance from the Galactic Core. Earth is in a zone where thoughts are slow and FTL doesn't work. Go into the unthinking depths and even that stops. But head rimwards? That's when things start getting odd.
Thinking as a writer, what defines this loss of consciousness? Do they sleep? Do they lose a sense of self? Do they cross that difficult-to-define transition between intelligence and instinct? Does this only act on "biologicals" and thus would an AI be immune? (It is strongly hinted that at least computing is possible because it would be very hard to pull off all this radio trickery without).