For a long time, I never gave sleep science much thought. The closest I came to probing what transpires when we close our eyes at night was putting a friend's hand in a cup of warm water to see if he'd piss himself. But recently, one Tuesday night, I was lying in bed alone, in an empty flat, when an ear-splitting noise woke me up. It was a terrifying – and terrified – shriek. A blood-curdling scream. A woman's voice. It sounded like my sister. It sounded like she was struggling.
My heart was racing and, for maybe ten seconds, I was paralysed. I couldn't move or make a sound. Then it passed; my muscles relaxed, I stopped jerking, the piercing scream died away and my eyes welled up.
That wasn't the only time this has happened. In fact, it's becoming a fairly regular occurrence; my journey to sleep has been hijacked. I don't experience any long-term mental health problems, if that might be related; I'm not going to bed fucked up on acid, or drunk, most of the time; and I don't regularly take medication. So what could be causing these auditory hallucinations?
As I lay in bed last week after another one of these episodes, I decided to follow the most rational course of action: self-diagnose myself online. According to the web, I have "exploding head syndrome" (EHS), a form of hallucination where a person hears a deafening noise, like a bomb exploding, or – in my case – the hideous screams of a family member.
Dr Brian Sharpless, an Assistant Professor at Washington State University, is an expert in exploding head syndrome. He happened to be in the UK for a couple of weeks recently, so I got in touch to arrange a meeting.
The earliest I could meet Sharpless was a week later, so in the days that followed our correspondence I did what I could to stop the screaming from happening again. I'd worked out that these episodes seem to happen when I'm not that tired or when I go to bed sober. So, I decided, the best thing to do was head to the kind of gay bar where sobriety and sleep are the very last things on your mind.
On the night bus home, sweating out the vodka, I broached the topic of EHS with Elle, a friend over from the US, assuming she'd think I was losing it. "Sometimes, my ex-girlfriend used to say she'd hear her father screaming in her ears, not for very long, before waking up with a jolt," she responded, unfazed. Turns out these episodes are more common that I'd expected.
The following Wednesday, I found myself sat in The Holy Inadequate, a pub on the outskirts of Stoke on Trent, opposite a stranger who was going to tell me why I hear screaming in my sleep. Dr Sharpless was speaking at the Stoke Sceptics Society, which seemed to be the sole thing happening in town that night.
"It usually happens just as you're going to sleep, or when you're about to wake up," Sharpless told me. "You hear a massive, loud explosion. Some people hear it outside, in the environment, while others hear it inside their head. Some people even feel the sensation that their head is actually exploding."
It often happens when you're off your sleep cycle, says Sharpless, who has conducted some of the most extensive research into the syndrome.
In 2011, he executed a study that used a sample of 36,000 people. "What I discovered was that about 8 percent of the general population, 28 percent of students and 32 percent of psychiatric patients had experienced exploding head syndrome at least once," he told me. Students, like psychiatric patients, have intermittent sleeping patterns, an apparent cause of the exploding head feeling.
Scientists have an array of explanations for EHS, but there's one that Sharpless argues is the most likely: "There's a part of your brain stem called the reticula formation. When you're going to sleep, just like a computer, your brain has to shut down in stages. What we think happens with exploding head syndrome is that – rather than shutting down – your auditory neurons fire all at once. It's this, we think, that causes these noises."
It seemed a rather dull explanation for this very visceral experience, but did at least reassure me that I wouldn't need to start seeking out an exorcism. Sharpless, however, did share a few of the more colourful theories about EHS with me – the first being gang-stalking.
"Gang-stalking is where a group of people spy on and torment you, and in this instance cause you to experience these sensations," said Sharpless, explaining that some EHS sufferers believe they're being targeted by a government agency of some sort. "They believe these agencies are using a microwave energy generator, and they point it at them while they're sleeping," he continued, "and it causes the massive explosion."
Whether these secretive spooks firing ray-guns at civilians actually exist or not, it's hard to say – Brian reckoned the guns would be expensive to produce, and I couldn't fathom a reason why any government agency would want to expend time and resources to wake up innocent people, before fleeing into the night, like the little bastards who knock-knock-ginger your nan.
Another explanation is that it's mobile phones causing the discomfort, but Sharpless' final offering was my favourite.
"I don't know about here in the UK, but in the US there was a big switch from passive to active water and electricity metres," said Sharpless. "A lot of people think this is how the government is spying on us, and causing us to experience these explosions."
What if he was right? I mean, my flat does have electricity and a water supply.
I got in touch with Southern Water and NPower to find out if they were behind the screaming: "Are your meters spying on us for the government and or causing me to hear noises in the night?" I emailed their press team.
"I am sorry to hear that you have suffered from 'exploding head syndrome'," came the response from Southern Water. "As you will know, doctors suspect the condition is caused by problems which occur for some when the brain shuts down when falling asleep – not by water meters. Let me reassure you that Southern Water is not installing smart meters."
Tellingly, NPower never got back to me.
Sharpless didn't think my sleep condition was too much to worry about. For other people, it can be debilitating to the extreme. In one case, a guy Sharpless met experienced these explosions up to seven times a night. In cases like that, it can lead to a fear of sleeping, serious anxiety and insomnia.
There hasn't been enough research done to find a cure yet, but experts reckon anti-depressants and anti-seizure pills may be helpful. "They don't make it go away, but appear to turn down the volume," says Sharpless. "In some other studies, just educating the patient has reduced the frequency."
I don't really know what's going on inside my head – whether the screams are the product of malfunctioning neurons, NPower mind games, or if I just have childhood issues relating to my sister that I should really see a therapist about. But if my meeting with Sharpless taught me anything, it's that this exploding head syndrome affects far more of us than I'd imagined.
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