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Comment by travisl12 | Hacker News Reader

I'm actually the opposite. In that I see flashes of light when I hear sounds (when my eyes are closed in a dark place). Happens all the time when I'm laying in bed before I fall asleep at night.

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I had that too. From an engineers perspective it looks like there is a coupling between the auditory and visual system/nerve. It makes sense that it only happens when you are lying in bed because there is no sensory input and the 'gain of the signal amplifier' is at maximum.

And if you're tired parts of your brain fall asleep before the entire brain, so you could be more attuned to more primitive sensory effects.

Do you mean sounds that are real or imagined? Reading this article made me look up this phenomenon I sometimes experience, and it turns out it's a documented thing: https://en.wikipedia.org/wiki/Exploding_head_syndrome

Thank you so much for the link! I've experienced it too and always wondered what it's called. It happened multiple times, over a period of a couple weeks. It always occured at the worst time - the moment where you actually fall asleep. It's definitely related to the twitching many people experience during this stage [0], as I thought.

It can be really intense: an extremely loud sound, a bright flash of light and jerking of the neck muscles. It became stronger every time it happened - until it suddenly went away completely.

[0] https://en.wikipedia.org/wiki/Hypnic_jerk

In the past, I've also suffered from sleep paralysis, so it's interesting that the two are possibly linked.

I used to experience sleep paralysis as a teenager and it was terrifying until I worked out how to end it (stay calm and focus on wiggling a toe).

It always left me wondering how many stories about alien abduction etc were related to sleep paralysis. I read once that a feeling of being watched was common with sleep paralysis.

> I read once that a feeling of being watched was common with sleep paralysis.

I've only experienced a couple of times, but that was the most noticeable thing about it. I knew about sleep paralysis before I first experienced, so it didn't really concern me (as soon as I realised I was awake but unable to move, I knew what it was and roughly what to expect), but glancing over to my doorway and seeing a vague silhouette just standing there watching me is somewhat disconcerting nonetheless.

Interesting, I never knew there was a word for this. I get the "plunging into a bottomless pit" version myself.

This seems like the closest thing to describing a thing I sometimes experience, that I call a "glitch" or a "reboot". It feels like there's just a momentary… zap, or something. Maybe akin to pressing the degauss button on a CRT. Just a split-second interruption in normal processing, usually accompanied by a brief popping sound and/or sensory zap. It's hard to explain.

I really miss that button.

No, it's definitely real sounds. Generally pipes or creaking staircases.

Count me in. My LCD monitor gets hot with usage all day, and is next to my bed (very close to my pillow). I turn it off just before going to bed. In a few minutes, the monitor cools down, and the plastic makes a crackling sound. Boom. Flash of light.

I experience this too. I'd be close to asleep and the floor may creak, or the radiator may ping, and it will turn into fireworks that look like a particular word in a particular font in a particular color.

Freaky stuff.

That's the experience I have, except that I don't have to be near sleep. Leafblowers and those 'safety' beeping noises on commercial vehicles are the bane of my life.

I see weird flashes when I close my eyes, especially when I close them hard. Not sure if this is a similar phenomenon.

That's most likely related to the pressure you exert on the retina. Close your eyes and press on you eyeballs, it should be even more intense.

Isn't that a warning sign of a possible or impending detached retina?

I've had it for as long as I can remember, so I don't think so. I do have poor vision though.

I think that's pretty common. At least, it happens to me, and I've mentioned it to several friends who said "oh yeah, that happens to me too"

+1 me too

There is a really cool 360 video of this actually by Discovery VR. Just watched it a couple days ago in my headset and learned about synesthesia. Is this what you have maybe? Seems like a pretty cool super power! ;) https://www.youtube.com/watch?v=obrBAysVef0

I get that. It's not just a flash, either; it's usually a highly regular geometric pattern, like a checkerboard or something like [this](http://aleph0.clarku.edu/~djoyce/poincare/tess_5_4.gif).

Do the patterns move or change color?

No, it's a very bright, instantaneous flash; just a hanful of milliseconds, like a flashbulb going off. There wouldn't be time for movement.

I get this too. They are slightly more regular and monochromatic geometric shapes than your example. I suspect the shapes may vary according to the loudness and suddenness of the noise, e.g. something big and heavy falling off a shelf in the room vs a car door slamming outside. I suspect I'd also see them in the day time if my eyes were closed, but there is so much other light and sound that the opportunity doesn't really arise. Like you say they are so fleeting that its hard to say the patterns move or change colour, but there might be a brief change as they flash in and fade.

I have to show this post to my wife when she comes back home. She told me once that she remembers seeing colours for every loud noise since she was a kid. She even thought that everybody experienced sound/sight synesthesia the same way, and remembers the day she found out her siblings didn't.

I also have this. Intensity of the noise correlates to the brightness of the flash. Also, it isn't every noise for me. "Sharp" noises, like a door closing or my cat knocking a book off a table, etc make the flash. The heater hummin. Along in the background does nothing.

I get this too, but it's always white, and usually flashes from the direction of the sound.

Those are floaters and flashes... https://www.aao.org/eye-health/diseases/what-are-floaters-fl...

No that's something completely different. travisl12 is talking about the 'exploding head syndrome'.

edit: no he's isn't, I mixed it up. He's talking about something related to the coupling of visual and auditory senses, e.g. the floor creaks and it causes the sensation of light.

No they're not. Why would you think that people would not be able to correlate the visual phenomena with the auditory stimulus? The article you link to doesn't even mention auditory phenomena so I don't know why you thought it would support your claim.

Also, please consider that it's extremely rude to just invalidate peoples' experiential claims, although I'm sure you didn't intend your comment in that spirit. Synaesthesia is a well-documented neurological phenomenon and you've just made yourself seem ignorant rather than clever.

Yeah, and the visual patterns seem to somehow relate to the character of the sounds. I've always wondered if I'm seeing a 2D spectrogram of the sound, or something similar.

I get that all the time too: Someone slams a door when I'm laying down, and it's like a flash going off in my face.

That's Exploding Head Syndrome (https://en.wikipedia.org/wiki/Exploding_head_syndrome)

Err, no it's not: Individuals with exploding head syndrome hear or experience loud imagined noises as they are falling asleep or waking up.