Invasion of the Demon Spiders, in 3-D!

So, I wake up in the middle of the night, as sometimes happens. I look up at the low, slanty ceiling above my bed, and see, or think I see, a huge damn spider, body bigger than a man's fist, legs spanning more than a foot, on the ceiling above me. I run hollering out of the room. ("Hollering" sound tougher than "squealing," right?)
It then occurs to me that the suburbs of Chicago are not generally known for harboring spiders large enough to eat small rodents in one sitting, and I cautiously venture back into my bedroom. There was nothing there.
So, I've started to hallucinate giant spiders. No more scotch before bed, I promise.