One of the most interesting facets of the human body is the way our brains sometimes "generate" information. The brain can't stand being unstimulated, so lacking sensory stimuli, it invents or exaggerates stuff on its own.
It's like the blind spot in your eye, which is filled in by the brain. But it manifests in so many other ways too. Think about getting up in the middle of the night, let's say to get a glass of water. It's dark, and silent. So your brain desperately tries to fill in gaps of perception.
As you slide off the bed, you'll swear your ears are picking up the sound of your own footsteps, even if you're stepping lightly and without any kind of footwear. In this case, there's very real senses that your brain is amplifying, and maybe even misinterpreting- the pressure of weight on your feet being "misread" as something different.
The kitchen is a place with so many smell-heavy memories associated with it. As you enter it with your empty cup, olfaction centers in your brain will start going wild trying to create something from nothing to fill in that gap. Usually, the experience of this is a faint, almost metal-tinged scent, kind of what you smell on the metal slide of a hot playground.
Your vision is not exempt from this as well, especially in areas of high contrast. If the interior of your apartment is dark, and there's soft light coming in from nearby windows, your neurons cling to that. At the periphery of your vision, you might start to notice the light "dance" a little. Shadows will blend just a tad as your sensory neurons try to keep up with changing lighting conditions. Sometimes, your brain fills in this "movement" as familiar shapes.
The burble of water coming from the sink is a comparative sensory feast for your brain, and it almost dispels all other "false" inputs.
When the sink is shut off, though, your brain is going into overdrive. It just got what it needed, and it now expects that level of stimulation- so it's gonna start inventing all sorts of things. You might start to see those dancing shadows in areas for smaller contrast now- lights from kitchen clocks, color changes or art on your walls, indicator lights on computers- coalescing into strange, thin humanoid shapes that dispel the moment you look at them. Makes sense though- humans are what we see moving around the most on a day to day basis, and our brains just work on pattern recognition. They fill in what you know, and when you add more information by taking a peek, your brain settles down.
Walking back to your bed, you might notice that the footsteps that once seemed so loud now don't seem loud enough, as if the sound is falling dead before it can carry. The floorboards, which used to make you jump when they creaked, now make no sound. Your brain is slowly normalizing, and doesn't need to fill in those gaps anymore. Hopefully that will help you get back to a restful sleep.
You lie down back in your bed, take a sip of that water, and for a moment look at the room around you. As you slowly fall asleep, the last errant "misfirings" of your brain will come together in more "comprehensive" ways. The dancing shadows from your peripheral vision might start showing up in your direct line of sight. They'll probably look like a figure coming towards you, as those shadows occupy more of your vision. Pattern recognition is a powerful thing!
The last moments before you fall asleep are where your mind is going wild, trying to put together so many different inputs, both real and false. You might feel chills, or even a cold hand on your leg. It'll pull from memory as well. As darkness falls across your vision, the shadows may contort into the face of a loved one you left behind long ago, sitting atop a wiery, inhuman body.
Make sure to get a restful sleep, and ignore these stimuli. Ignore the feeling of breathe in your neck when you close your eyes. Ignore the feeling of your blankets parting as you drift away. Ignore the figure that was formed from those shadows. They'll be gone come morning.
They'll be gone come morning.
They'll be gone come morning.
