Apparently I ' m very allergic to cats . Did n't know that exactly until just these past two weeks . I fell asleep on the couch in the living room two weekends ago and had terrible sinus reactions . But here 's the rub .

Why did falling asleep on the couch and becoming ill lead the speaker to realize they must be allergic to cats ?
The cat hair is very prevalent on furniture in the speaker 's house , and the couch is one example