# Almost asleep...Loud sound causes flash of light **URL:** \ **Category:** Factual Questions\ **Created:** [April 10, 2003, 8:02pm UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875 "2003-04-10T20:02:29Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Chihuahua](https://avatars.discourse-cdn.com/v4/letter/c/dec6dc/32.png) [@Chihuahua](https://boards.straightdope.com/u/Chihuahua)\ **Post date:** [June 7, 2014, 7:54am UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/21 "2014-06-07T07:54:01Z")
Same thing happens to me. I also see it accompanying a hypnic jerk. ---
**Author:** ![RiCu](https://avatars.discourse-cdn.com/v4/letter/r/e19adc/32.png) [@RiCu](https://boards.straightdope.com/u/RiCu)\ **Post date:** [June 7, 2014, 8:00am UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/22 "2014-06-07T08:00:01Z")
> [@sidecar\_jon](#): > > There is the dramatically named “Exploding head syndrome”… > [Exploding head syndrome - Wikipedia](http://en.wikipedia.org/wiki/Exploding_head_syndrome) I’ve had this in the past, but it’s not the same as what’s described in this thread. EHS has both the sound and flash coming from inside the sufferer’s head. What’s described here is a visual reaction to an unexpected noise. ---
**Author:** ![Amyirie](https://avatars.discourse-cdn.com/v4/letter/a/41988e/32.png) [@Amyirie](https://boards.straightdope.com/u/Amyirie)\ **Post date:** [August 8, 2014, 3:47pm UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/23 "2014-08-08T15:47:17Z")
For the past 3-4 years, I too experience images while falling asleep accompanying a startling sound. For me, as I am falling asleep, if I hear a sound like a door shutting, or a voice, I immediately see a black and white geometric pattern flash in front of my eyes (my eyes are closed). This pattern is always black and white, and always a geometric pattern…it never changes. The image lasts for a second, and it is weird but I know that every image that I see is a new one, and I never see a repeat image. At the same time as seeing the image, my heart races as hearing the sound and seeing the sudden image startles me. This happens about 4-5 times a week, and as mentioned before has been happening for about 3-4 years. Does anyone else share any experiences like mine? ---
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [August 8, 2014, 5:05pm UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/24 "2014-08-08T17:05:40Z")
See Post 19. ---
**Author:** ![buchanann](https://avatars.discourse-cdn.com/v4/letter/b/c77e96/32.png) [@buchanann](https://boards.straightdope.com/u/buchanann)\ **Post date:** [December 16, 2014, 8:25am UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/25 "2014-12-16T08:25:06Z")
For the past several years, I’ve been having this experience more and more …While falling asleep, a sound of any kind will produce a flash of some kind of black and white geometric pattern in my eyes, lasting only . For me, every time it happens the pattern is different and unique, but it always seems impossibly perfect, as if made by a computer. Sometimes I wonder if we aren’t actually living in some kind of “Matrix” and these little alarming sounds are causing a glimpse through to the computerized code of it all. But really, I’m sure there is some kind of scientific explanation for this phenomenon. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [December 16, 2014, 11:23am UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/26 "2014-12-16T11:23:19Z")
I am surprised that no one has offered a medical explanation: > [@](#): > > Flashes > > Otherwise known as ‘photopsia’, flashes describe the subjective sensation of seeing a light in the absence of an objective stimulus. This may present as scintillating lights, an arc of light or a feeling like a light-bulb has just flashed on and off in the periphery of vision. Flashes are caused by improper stimulation of the eye’s retina, or the optic nerve, which the brain interprets as light. This could be traction of the retina, for example. > > Causes of flashes > > Retinal traction > The vitreous is the viscous filling occupying most of the globe. It is loosely attached, at its periphery, to the retina. In some parts, it is more firmly adherent. Any condition which causes it to contract (eg, fibrosis as a primary problem or following haemorrhage, the natural progressive liquefaction that occurs with age) has the potential to result in flashes, as the vitreous pulls on the retina in the process. These conditions include: > > Vitreous detachment (may also occur with floaters). > Retinal detachment. > Proliferative diabetic retinopathy. > Sickle cell retinopathy. > Retinopathy of prematurity. > **[Flashes, floaters and haloes](https://patient.info/doctor/flashes-floaters-and-haloes-pro)** > > This article covers all different floaters, flashes and haloes. Discussing the floaters, flashes and haloes that are common and rare. Written by a GP. ---
**Author:** ![Omar\_Little](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omar_little/32/269_2.png) [@Omar\_Little](https://boards.straightdope.com/u/Omar_Little)\ **Post date:** [December 16, 2014, 6:42pm UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/27 "2014-12-16T18:42:15Z")
Are your flashes accompanied with any of the following sensations: Is there a lingering smell of burned hair in the air? Do you have a sensation of having any of your bodily orifices violated? Is the tinging sensation in your ears that won’t go away? If not, I can’t help you. ---
**Author:** ![levdrakon](https://avatars.discourse-cdn.com/v4/letter/l/49beb7/32.png) [@levdrakon](https://boards.straightdope.com/u/levdrakon)\ **Post date:** [December 16, 2014, 6:53pm UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/28 "2014-12-16T18:53:56Z")
Me too. I get the flash of light, and sometimes a loud electrical pop in my head. Since we’re talking about weird head stuff, does this ever happen to anyone? I’ll be in bed thinking about something, roll over to my other side, and forget what I was thinking about. I roll back over the way I was, and remember. Weird? ---
**Author:** ![Hopeful\_Crow](https://avatars.discourse-cdn.com/v4/letter/h/da6949/32.png) [@Hopeful\_Crow](https://boards.straightdope.com/u/Hopeful_Crow)\ **Post date:** [December 16, 2014, 10:06pm UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/29 "2014-12-16T22:06:38Z")
I’ve gotten those flashes, too. Also, I’ve been woken up by what my brain interprets as an alarm going off. The building I live in now is lousy with smoke and fire alarms, and, probably since they’re so visible, I’ve always been a little worried about them going off and having to negotiate the stairs with my gimpy legs. So every once in a while, my brain seems to decide to hold a drill. “EEEEEEEP!!” It screams and I wake up, ready to jump out of bed, only to hear nothing. I lay there, waiting for the sound to repeat. Nothing. Stoopit brain with its stoopit emergency preparedness. ---
**Author:** ![Mitchie\_D](https://avatars.discourse-cdn.com/v4/letter/m/e274bd/32.png) [@Mitchie\_D](https://boards.straightdope.com/u/Mitchie_D)\ **Post date:** [March 11, 2016, 10:39pm UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/30 "2016-03-11T22:39:27Z")
This happens to me all the time. This is the only post I can find though where the stimulus is an external sound. Apparently there’s this thing called exploding head syndrome in which the same thing happens but the sound comes from inside your head. This has happened to me before, but more often the sound in my case is external, like a knock on the door, or the house creaking suddenly on a cold night. It’s happened to me a few times where the sound in my head is someone yelling my name, but I can’t find anyone else who’s had that experience, only a loud sounds like a gun shot. ---
**Author:** ![AJFU](https://avatars.discourse-cdn.com/v4/letter/a/e9bcb4/32.png) [@AJFU](https://boards.straightdope.com/u/AJFU)\ **Post date:** [September 29, 2016, 9:24pm UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/31 "2016-09-29T21:24:12Z")
I have the exact same thing as the first person who posted this. As I am nearly asleep, I’ll see a sudden flash of television static across my field of vision (with my eyes closed). It only lasts a split second, and is only brought on by sudden noises. It doesn’t even have to be loud, either. Something as simple as a door cracking is all it takes. It’s never been a problem, but I’ve always wondered what it was. They are, indeed, phosphenes. Specifically, “_ **auditory evoked phosphenes** _,” as described in [a 1982 study](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC491258/) of people with this exact problem. Almost all of them were diagnosed with [ischemic optic neuropathy](https://en.wikipedia.org/wiki/Ischemic_optic_neuropathy), a partial or complete lack of vision (usually sudden) that is brought on by a shortage of blood flow to the eyes. Although that does not sound like me, as I have had this since 2010, and I still have my vision, just as great as ever. [Another study from 1979](https://www.ncbi.nlm.nih.gov/pubmed/574208) states: “_ **The sound-induced phosphenes in these cases seemed to be a pathologic variety of hypnagogic hallucination. We theorize that under conditions of altered excitability and visual deafferentation of the brain, cells capable of responding to both visual and auditory stimuli become hyperresponsive to sounds** _.” I have [Hypnopompic hallucinations](https://en.wikipedia.org/wiki/Hypnopompic), and I guess I also have the [hypnagogic](https://en.wikipedia.org/wiki/Hypnagogia) variety as well. I also have other issues as well, which may or may not be related, but I figured I would mention them: OCD (since 2003, when I was 10 or 11); eye floaters (since 2004); tinnitus (since 2010); and racing thoughts (since 2014). ---
**Author:** ![Banksiaman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/banksiaman/32/3334_2.png) [@Banksiaman](https://boards.straightdope.com/u/Banksiaman)\ **Post date:** [September 30, 2016, 5:17am UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/32 "2016-09-30T05:17:27Z")
interesting discussion. i used to get something very similar, and would have assumed sleep apnea - something like an initial apnea breath stoppage before the brain is entirely asleep triggering a very insistent wake up ‘snap’. ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [September 30, 2016, 9:26am UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/33 "2016-09-30T09:26:08Z")
I get it, too. But it’s not loud noises. It’s anything that startles me. I always assumed it was that my eyes/vision was slowly turning off, and then the startling noise jolts them back into action. I’ve also had brain zaps due to medicine withdrawal. And, when I was having those, I found that the noise also caused this. It is slightly dizzying sensation that lasts moments. and feel like a low level of electricity went across your brain. Hence why I assumed it was in the brain. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [September 30, 2016, 3:31pm UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/34 "2016-09-30T15:31:51Z")
What a bunch of pathological hypnagogic hallucinators in this thread. ETA: band name. ---
**Author:** ![Boneface](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Boneface](https://boards.straightdope.com/u/Boneface)\ **Post date:** [April 14, 2017, 4:44am UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/35 "2017-04-14T04:44:28Z")
> [@AJFU](#): > > [Another study from 1979](https://www.ncbi.nlm.nih.gov/pubmed/574208) states: “_ **The sound-induced phosphenes in these cases seemed to be a pathologic variety of hypnagogic hallucination. We theorize that under conditions of altered excitability and visual deafferentation of the brain, cells capable of responding to both visual and auditory stimuli become hyperresponsive to sounds** _.” I have [Hypnopompic hallucinations](https://en.wikipedia.org/wiki/Hypnopompic), and I guess I also have the [hypnagogic](https://en.wikipedia.org/wiki/Hypnagogia) variety as well. I also have other issues as well, which may or may not be related, but I figured I would mention them: OCD (since 2003, when I was 10 or 11); eye floaters (since 2004); tinnitus (since 2010); and racing thoughts (since 2014). What the fuck? I have these exact same issues plus anxiety and insomnia. For me I see a flash of light at the same time as the sound or slightly before I perceive the sound. The flash of light changes shape and color each time. Different sounds will have very different colors and shapes. Most are bright white in the centre with colors radiating outwards in a repeating shape or pattern. What’s bizarre to me is how the visual will appear before the sound sometimes. And the size of the flash corresponds to the volume of the noise. I get startled by it every time it happens. I sometimes see flashes when I’m awake too, but rarely. I can’t believe so many other people experience this! I just decided to google it after my SO told me he doesn’t experience this when I asked him. ---
**Author:** ![JKellyMap](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jkellymap/32/15880_2.png) [@JKellyMap](https://boards.straightdope.com/u/JKellyMap)\ **Post date:** [April 14, 2017, 10:33am UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/36 "2017-04-14T10:33:45Z")
Welcome to the Dope! This thread started back in 2003, but that’s fine – we’re glad you found the information helpful. Others may, as well, so it’s just as well it’s been revived (again). ---
**Author:** ![bardos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bardos/32/1069_2.png) [@bardos](https://boards.straightdope.com/u/bardos)\ **Post date:** [April 15, 2017, 11:27pm UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/37 "2017-04-15T23:27:55Z")
I was totally surprised to read this thread. I get something similar. Started happening only last year. Happens in the middle of the night while I’m fast asleep. A noise, large electric crack, and a giant whitish/yellowish spark fills the center of the room. Wakes me right up from a deep sleep. The first time I thought the house had been struck by lightning… or a short circuit somewhere… but nothing, everything totally normal in the house. It has happened a couple of times since. I have even moved countries and it happened to me where I am now as well. ---
**Author:** ![JBAD](https://avatars.discourse-cdn.com/v4/letter/j/b4bc9f/32.png) [@JBAD](https://boards.straightdope.com/u/JBAD)\ **Post date:** [January 20, 2018, 1:48am UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/38 "2018-01-20T01:48:39Z")
I’ve had exactly the same for years, I just literally had it happen again so I thought I’d google it. As I didn’t know what to put I just put in the key words black and white shapes eyes closed and found this thread. Every time I’m startled by a noise when falling asleep, the noise manifests itself as a brief black and white pattern which is completely geometrical and symmetrical I find this experience a pleasant one and although very brief as something that is a glimpse into a part of the brain that we rarely use. Maybe it’s us actually seeing the electrical impulses of the brain for a brief moment as a reaction to the sudden interruption of the tranquility in the space between being awake and asleep a bit like the R.E.M. phase. I’d like to be able to take a screen shot of the image so I could explore it more and it’s very frustrating to see its beauty for such a short amount of time because every time it happens the pattern is always different. Does anyone else have the same sort of experience? ---
**Author:** ![j666](https://avatars.discourse-cdn.com/v4/letter/j/9de0a6/32.png) [@j666](https://boards.straightdope.com/u/j666)\ **Post date:** [January 20, 2018, 2:25am UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/39 "2018-01-20T02:25:59Z")
It’s been awhile since neurophysiology, but if I remember correctly: Neurons respond to specific stimuli above a specific threshold. This much pressure, and no less, will trigger a pressure sensing neuron. I believe it has been established finally that some people’s neurons will fire at a lower stimulus (so, no, Mom, I wasn’t a wuss about pain, my neurons just fire at a lower threshold). However, stimuli in great excess will trigger neurons which are not intended to respond to that stimulus, and the most common example is “seeing stars” if you hit your head. It is possible that the neurons in your eyes are more easily trigger than most people’s by excessive sound, and that you only notice this when there is very little light stimulus. You have magic eyes. ---
**Author:** ![Beckdawrek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beckdawrek/32/3647_2.png) [@Beckdawrek](https://boards.straightdope.com/u/Beckdawrek)\ **Post date:** [January 20, 2018, 2:41am UTC](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875/40 "2018-01-20T02:41:59Z")
I had my ‘bell rung’ one time in my teens. I saw the actual stars like in cartoons. Years later I experienced a slight head injury. No stars this time, but I had a massive headache, and my sleep for several days was disturbed. I probably had a concussion, undiagnosed. This loud sound/light flashing has occurred in my near sleep state, alot. I attributed it to my 2 injuries resulting in a slight brain damage. Or Aliens. [Previous page](https://boards.straightdope.com/t/almost-asleep-loud-sound-causes-flash-of-light/167875.md?page=1)