There are some diseases with pretty gnarly names, and they very rarely live up to the hype. There’s walking corpse syndrome, for example – nothing to do with the oncoming zombie apocalypse, but a rare neuropsychiatric condition. Or alien hand syndrome: not the result of UFOs taking control of your limbs and jigging you around like a puppet, but the result of one of your hands deciding it’s going to be uncooperative.

However, few conditions have as dramatic a mismatch between name and pathology as Exploding Head Syndrome. Think about it: if your best friend told you they had it, you’d be wondering how long you had left with them.

In fact, your buddy is fine – they’re probably not about to spontaneously combust. Let us explain.

What is Exploding Head Syndrome?

You’ll be relieved (or disappointed, depending on how much you like gore) to know that Exploding Head Syndrome doesn’t actually make your head explode.

For those who have the condition, though, it’s definitely disturbing. Also known as episodic cranial sensory shocks, Exploding Head Syndrome is a sleep disorder characterized by hearing crashes, bangs, or other loud noises. They usually happen suddenly, just as you’re trying to nod off or when you wake up in the night, sometimes accompanied by vivid flashes of light and muscle jerks.

“Strangely enough, it happens when people aren’t actually asleep,” explained Professor Brian Sharpless, an expert on the condition, in an interview for the BBC’s Science Focus podcast. “But they feel that they are – they have sleep state misperception, is what it’s called.”

“When Exploding Head Syndrome occurs, people are really in a state of deep relaxation that happens right before sleep,” he said.

So, imagine you’re falling asleep, in that deep relaxed state, then suddenly this happens:

“I started hearing noises, it sounded like pure static, electricity and it got louder and louder till I heard a loud exploding like doorbell-bang. So loud, I wanted to scream. But I could not. My body was not moving. I felt a terrible pain in my head, along with electricity in my arms back, and legs. My eyes wide open, my vision full of dots and colorful patches and flashes of lightning. I thought I was having a seizure or a stroke,” user Planetmclulu wrote on Bored Panda.

Sounds terrifying, right? Here’s the kicker: nobody else can see or hear this. The explosions, you might say, are in your head.

How common is Exploding Head Syndrome?

Strangely, we don’t have much data on how many people have this explosive condition. It’s been in the medical literature since the 1870s, but it’s not been studied all that much.

We don’t even know who is more susceptible to Exploding Head Syndrome – there are records of patients younger than ten and older than 80, and as yet no genetic link has been found.

It seems to affect women slightly more than men, though: a random person with Exploding Head Syndrome is about 1.5 times as likely to be a woman than a man, according to researcher Brian Sharpless. But even this figure should be treated with caution, since there’s just not enough standardized data to draw many conclusions.

Interestingly, though, one thing does seem to be true: it’s not as rare as we thought. In 2020, researchers at Goldsmiths University in London published the results of a survey of nearly 7,000 people – more than half of whom reported having experienced Exploding Head Syndrome at some point.

Why isn’t the condition more well-known? Well, the clue is in the details: 35 percent of people in the survey said they only experience the condition a few times per year, and a further 40 percent said they had only had a few episodes ever. Let’s face it – have you never been woken up in the night by a car backfiring or a peal of thunder, only to calm yourself down and go back to sleep without thinking too much about it?

What causes Exploding Head Syndrome?

There are a few theories on what’s behind this condition, but none are accepted as medical gospel.

Current research does have a pretty good idea of what’s going on mechanically, at least: “When we fall asleep, the reticular formation of the brainstem (a part of our brain involved in consciousness) typically starts to inhibit our ability to move, see and hear things,” explained Alice Gregory, a Professor of psychology and exploding head researcher, in an article for The Conversation.

However, Exploding Head Syndrome is likely a sign that something’s gone slightly wrong with this process, researchers think.

“When we experience a ‘bang’ in our sleep this might be because of a delay in this process,” continued Gregory. “Instead of the reticular formation shutting down the auditory neurons, they might fire at once.”

People with Exploding Head Syndrome often don’t notice any particular triggers before an episode, but those who do often relate it to stress, or sometimes medication.

“For whatever reason, maybe sleep disturbances, anxiety could be a trigger, or possibly even a genetic mutation on chromosome 19 – if you have any of those things, you're more likely to have sort of a ‘mistake’ as you're going to sleep,” explained Sharpless.

“If you have disrupted sleep, or you’re jet-lagged, or especially if you drink alcohol or caffeine before you go to sleep, you're far more likely to experience these strange sleep experiences.”

Of course, for a minority of respondents in the Goldsmiths study, the cause was obvious: they thought the loud noises they heard were simply evidence of the supernatural.

Is Exploding Head Syndrome dangerous?

Put simply: no. It’s often scary, sometimes debilitating, but not intrinsically dangerous.

“Although they can be dramatic and scary, EHS episodes are relatively harmless,” explained Sharpless in a statement. “However, a small percentage of people have them so regularly that normal sleep patterns are disrupted and others worry that EHS episodes may be a sign that something is seriously wrong with their mental or physical health.”

In fact, the worst effect of Exploding Head Syndrome is likely psychological. For the minority of people who experience these explosions every night – or even more frequently than that – going to sleep can become a daunting task, especially if you don’t have an answer for what’s going on.

“Our hope is that future studies will help to identify effective treatment options for the minority of people who suffer from severe [Exploding Head Syndrome],” Sharpless said.

Can we treat Exploding Head Syndrome?

As you might have already guessed from the lack of solid data on the condition, there isn’t currently a treatment known to cure Exploding Head Syndrome. The good news is that for most people, that’s not really a problem.

“A study by Gautam Ganguly, a neurologist at the University of Southern California’s Keck School of Medicine, suggested that the best treatment for EHS may be simple reassurance that the condition is benign rather than an indication of something more serious,” wrote internal-medicine physician Rod Tanchanco in The Atlantic.

“[Ganguly] reported the case of a 57-year-old man whose symptoms had not recurred six months after doctors convinced him that his EHS was nothing more than an inconvenience.”

If that doesn’t work, there are a variety of medications that can be offered – like anti-seizure drugs and anti-anxiety meds – but as with so much around this condition, there’s not much in the way of hard evidence backing the use of any one pharmacological treatment over any other.

The real goal, Sharpless said, is to find self-help therapies that could reduce the frequency and severity of attacks.

“If we [could] find out that engaging in certain bedtime behaviors might make [an episode] less likely to occur, that would be important information to get out there,” he said. “Not just to psychologists and psychiatrists but to general practitioners and other folks … that would be helpful.”

What should I do if I have Exploding Head Syndrome?

First of all, don’t worry. Exploding Head Syndrome may have a scary name and scary symptoms, but it’s really a benign condition. If it’s really bothering you, you should see your doctor – but be prepared to be the one advising them, Sharpless says, as most non-specialists are not familiar with the syndrome.

“Sleep specialists and neurologists are probably going to be fairly familiar with Exploding Head Syndrome – at least [they’ll] know the name and … its core features,” he said. “But if you’re working with a general practitioner, you might need to give them a bit of background, so that they know it is legitimate thing – and also that it can cause some distress!”

However, for most of us out there who sometimes wake up in the night hearing loud, frightening noises, it's unlikely to be a long-term problem – it’s really just a sign something’s gone a bit wonky while you’re dropping off to sleep.

“Sleep is an amazingly complex process and there's a lot that can go wrong,” Sharpless said. “One of the ways I like to think of Exploding Head Syndrome is that it’s another in a long list of the ways that sleep can go wrong.”