Have you ever heard of Episodic Cranial Sensory Shock?

Me neither. It's a real thing though with the much more interesting colloquial name Exploding head syndrome. A recent article (here) gave a decent enough rundown, though it left out a little bit, too. You can't pack as much into an article as you can into a book. But books take a loot longer to write. Trust me, I know. I've written a few¹. So today, as a public service of sorts, I'm going to add some discussion about the syndrome with the wonderful but not quite accurate name.

To begin with, which I can say even though I'm a couple paragraphs beyond the beginning, Exploding Head Syndrome doesn't mean that your head actually explodes. That would be messy and people would probably notice. No, What EHS² is, is when you wake up to the sound of an explosion that only takes place in your head. It can be very disturbing. No one wakes up like that and thinks, "Huh. I wonder what that was?"

You're much more likely to spend a few moments feeling terrified and wondering what just happened before settling on the, "It was all a dream" explanation. Even then, it may take a while for your heart rate to come down enough to get back to sleep. Most people never experience it, thankfully. For those who do it's not very common. But you know how the brain is. No two people are quite the same and you can't count on what's "normal" being the way things are in an particular case.

There's another, related phenomena that happens sometimes. That’s when, instead of an explosion, you hear a very loud angry voice yell something like, "Get out of my house!" Or "my room!" or, possibly creepiest of all, "my bed!" Actually the creepiest one would be if it said, "Get out of my skin" but I've never heard of anyone hearing that one. Maybe someone will now, though. Sorry.

You hear of the "Get out of my house" thing in connection with ghost stories, sometimes. But more commonly, it's just something people sort of hear as they wake up from having been sort of asleep. It's weirdly specific, though, isn't it? No one ever reports a disembodied voice saying, "Good morning" or "Have you seen my car keys?" The volume of what it says (always a shout, never a whisper) is similar to the volume of the explosions. That seems like it should be a clue to what's happening but it might just mean that unexpected mental noises have to have a certain amount of volume to get your attention.

Neither exploding head syndrome nor the voice one are likely to happen when you're asleep or when you're awake. It's when you're in between, just falling asleep or just waking up. Lots of weird stuff can happen then. Both of these are classified as parasomnias. According to The Neuroscience of Sleep and Dreams³, parasomnias are, "disruptions of behavior or consciousness during sleep." That was a really useful definition, wasn't it? (Yes, I’m being sarcastic.) Sleep walking and talking in your sleep are parasomnias, too. So are night terrors and nightmares, which apparently only count as nightmares if they wake you up⁴.

And don't forget the hallucinations. Or as the scientists call them, hypnagogic hallucinations which is a fancy way of saying you see (and hear and feel) things that aren't really there because you're not really awake yet (or asleep yet) even though you think you are. It seems that falling asleep and waking up are times when your brain is most likely to play tricks on you.

Have you ever had the one where you thought for sure somebody was standing by the foot of the bed watching you? And maybe you were paralyzed to boot? Yeah. That's probably just the brain continuing to dream and the body acting like you're still asleep, even thought you think you're awake. Sometimes people blame that on aliens, instead. The hard thing for scientists is they have no way to distinguish one from the other. No blood test or brain scan can tell you what happened. If you believe in aliens, it was probably aliens. If you don't believe, then it couldn't have been.

And it's impossible to reliably recreate these experiences in a lab. You can't tell somebody, "Go to sleep. Later, when you wake up, we want you to hallucinate aliens standing next to your bed." Well, you can tell them but it won't do any good. What happens, happens. What doesn't happen, doesn't.

So most of the research into parasomnias is in the form of questionnaires. "Have you ever experienced episodes of sleep walking, sleep paralysis or the sense that your head was exploding? If yes, please describe the circumstances." And I'll bet actual money that they don't follow that up with, "Are you sure it was all in your head or could it have been ghosts, aliens, transdimensional beings or your crazy brother-in-law playing a practical joke on you? (Select all that apply)"

One point about the parasomnias that comes up over and over in the literature is that they are more common with people who have other sleep problems. Sleep apnea. Insomnia. Maybe depression and anxiety, too. All the things that make going to sleep a chore rather than the welcome break it should be. The why part is not at all understood. Sleep science is a very active field of research but even with the new imaging techniques (mostly meaning fMRI), solid answers are hard to come by. Getting a peek at what the brain is doing, which cells are firing, what chemicals it's producing, doesn't tell you anything about causes.

And the most important thing all the articles emphasize is that Exploding Head Syndrome has nothing to do with your head actually exploding. It just sounds like it. It's not dangerous at all! Unless, of course, it frightens you so much you have a heart attack. That would be inconvenient, dying from something weird because you didn't know it was harmless. I think that's the definition of ironic termination. Or as we call it at work, I.T.

Here's that prompt: "A surreal and symbolic representation of Exploding Head Syndrome and alien abduction. The image features a human head in profile, with a swirling vortex of abstract, fragmented shapes and bright flashes emerging from the head, suggesting sudden, disorienting noises. In the background, a faint outline of an alien ship hovers, casting an eerie glow. The colors of the vortex contrast with the cool, dark tones of the alien atmosphere, creating a dreamlike, otherworldly effect. The head appears both calm and confused, reflecting the strange combination of sudden noises and a mysterious abduction scenario."