Sometimes, about 10 minutes before I fall asleep, any mental visualizations I make with my eyes closed will distort and lose their sense of proportion. Like for instance, if I were trying to think of the image of an apple, it would either shrink down to the size of a pinhead, balloon to the size of jupiter, or even fluctuate between the two. Does anyone experience this phenomenon? Is there any pre-sleep preparation in the brain that explains it?
I get this, too. Don’t know what it’s all about, though.
Hypnogogic hallucinations. These are simple shapes and objects you see before going to sleep. Not full dreams but perceptual incidents with similar features to the more expansive experience of dreams. A lot of people have them. I can dig up more if anybody wants.
As a random aside I like the term hypnogogic delusions for the strange thoughts people (well… I) sometimes have before going to bed; I’m not sure if any actual sleep researchers use it though.
I did a google/wikipedia search on hypnogogic hallucinations, and what was described doesn’t really fit my experience. I feel in control of what I’m visualizing, just not of the distortions. Also, The visualizations aren’t that vivid, either–no different than during my waking hours, except of course for the lack of scale.
Thinking back, what I said about being in control of my visualizations is not necessarily true. I seem to visualize part of my body more often than other objects (No, not THAT part of my body, but I digress).
At times the amount of fluctuation in scale invovled is quite disorienting, but after opening my eyes the feeling, and the visualizations, go away. Of course, upon closing my eyes again, it comes back, and remains until I fall asleep a few minutes later.
Oh, and the site below provides some good information on hypnogogic hallucinations, FWIW:
http://www.macalester.edu/~psych/whathap/UBNRP/narcolepsy/hallucinations.html
I have had the size-perception thing a couple of times when I was a youngster. Once the adults had given me an antihistamine pill (this was when antihistamines were a new thing), and once when I was very sick and probably borderline delirious.
Cool sensation. You would look at something and it would appear to be enormous and very close, then tiny and very far away.
When I’m on the way to sleep, there’s a period where the thoughts come loose from reality and the logic begins to float. I only am aware of this when something wakes me in the middle of it.
The term covers every perceptual experience that you have while falling asleep that isn’t related to outside experience. The examples given are a mix of the typical and troubling experiences, but like dreams people have a wide variety of experiences. People who suffer night terrors and awareness during paraylsis are the most often reporters of their hypnogogic and hypnopompic imagery. Most people who don’t have troubling experiences don’t talk to clinical types about it. The normal experiences are obtained by survey.
Could it just be random firing of photoreceptors in your eyes? I’m pretty sure that’s what the colored spots are you see when it’s dark.
Random firings do not produce full objects, at least not in normal circumstances. You can experience visual perception without any sensation as the source. This is most typical during dreaming, but does happen when waking and falling asleep. In all cases the signals from the eyes are reduced. Bottom up signals have the advantage of a refreshing external source to overwhelm what ever hallucination top down signals are producing.
Basically if any of the brain areas responsible for visual perception become activated you may become consciously aware of an object, color, or so on. The areas that are likely to become active without any exterior sensation are those that cover the more abstract aspects of perception. Impressions of full objects with size, motion, and position are what get enough activation to remain stable and enter conscious attention. The neurons responsible for these activate the neurons responsible for the components and the image reinforces itself and you may get a sense of the component features. You can even get things shifting around as new neurons are activate and inhibition effects plus fatigue cause the pattern of activation to change. Once you open your eyes the images are going to fade in most cases.
When ever you don’t have this input phantom images have a chance to gain and maintain strength. What times don’t you have much stimuli? When you are going to sleep, sleeping, and waking up.