[Benares]

Thank you for posting this. I "suffer" from EHS but never knew there was a name for it.

Just as the WP entry says, I experience it just after lying down to sleep. Probably happens 10 or 20 times a year. A loud banging, crashing, or tearing sound occurs in my head. My heart rate goes through the roof immediately, but it's not scary at all. It's very odd. :D

[lisper]

Yeah, I actually have this too apparently, though it's very infrequent for me. I'm not sure what's weirder, that it happens, or that it has a name.

Just for the record, I actually found out about this here:

http://www.reddit.com/r/IAmA/comments/nrf8s/iama_26_year_old...

[stephth]

sound occurs in my head

What does that mean exactly? Could you describe it? Does it sound like physically outside but you realize by logic that it "didnt happen", or is it clear right away that it's an imaginary sound?

[Benares]

For me, it's usually like an electrical buzz. But sometimes it's more like a gunshot, a tearing sheet of paper, or an indecipherable vocal shout.

The sound does not feel dreamlike at all (like sounds you imagine while in a hypnagogic state.) I can imagine a first-timer might mistake it for an external event and rising in shock to look for the source of the disturbance.

The sound is of short duration (about 0.2s) and is loudest at the end of the sound, cutting off sharply into total silence ("...wwwWWWHOMP!") It's very loud, but not painful like a real report in a quiet room would be. The loudness feels like 120 dB or so. The sound is absolutely "pure," missing environmental cues like position, echo, and pressure. I perceive the location to be smack-dab in the middle of my head, not anywhere outside my physical body (a bit like headphones.) Because of this, and because I have been cued to the impending sound (see below), there is no danger of mistaking it for something real.

The chronology when my head goes boom:

T minus 30 seconds: I'm in bed, eyes closed. It always happens before or at the beginning of hypnagogia.

T minus 10 seconds: I get a feeling somewhat akin to a sudden pressure drop in my ears (but without any popping or physical symptoms). This is a cue that tells me to expect an explosion.

T: The pseudo-aural pressure cue suddenly ends by "transforming" into a short, explosive sound. Heart rate starts to rise rapidly. My eyes remain closed and my musculoskeletal system usually don't react, as the sound doesn't scare or surprise me.

T plus 5 seconds: Heart is beating as fast as it can go. At this point it feels almost exactly like right after snapping awake from a night terror, but without the fear component.

T plus 60 seconds: Heart rate begins to decline to normal levels.

[lisper]

It sounds like a real sound that happens outside me. For me, it sounds like a loud "whack" as if someone hit a baseball in my bedroom. It only happens as I'm falling asleep and it usually wakes me up. It takes a little while to figure out that it wasn't real, especially the first few times it happened.

[jerico2day]

this occurs with me periodically. It scares me in the same way someone hiding and going boo scares me. The first time you're really scared, after that it's just something that happens sometimes.

To answer your question, it doesn't sound like it's in my head. It sounds as if I were to play someone screaming or buzzing over some headphones.

[kiba]

It seems that you fall prey to the "typical mind fallacy". For example, some people thought imagination was just a metaphor, not something that people actually do. Turns out that people have different capacity of imagination.

I don't experience exploding head syndrome though.

Speaking of atypical mind, sometime I experience my vision become white entirely for a few moment. They are so brief that I am not sure that they occurs or they are just my imagination.

[bitanarch]

I occasionally experience the same thing during sleep as well - never knew there's a name for it. It used to scare me a lot when I was a kid, but after some time I've learned to control my fear when it happens.

It also seems to be triggered when I'm attacked by ghosts or monsters in nightmares, or when I jump off from a building in dreams - my brain seem to use that to simulate death in dreams. After which I'd either wake up or transition to another dream.

[bitanarch]

Looked though Wikipedia a bit.. apparently this may be related to something quite common call Hypnagogia.

http://en.wikipedia.org/wiki/Hypnagogia

Look under the "Sounds" heading - makes a lot of sense to what I'd experienced. The loud sounds happen when I'm either transitioning from or to sleep.

Jumbled speeches is another thing I'd experienced during such a state - it feels like it makes perfect sense when you're in the state. But if something wakes you up or you're somehow able to summon your conscious thoughts, you'd find the speeches you just heard were just a random stream of words.

[gommm]

Same here. It doesn't happen often, once or twice a month but has been happening since as long as I can remember so I always thought it was actually normal... I do seem to have it more when I'm very stressed.