Have you ever been drifting off to sleep and found that you simply can’t move? Or perhaps this has happened as you were waking up? During this experience, have you seen any strange things which aren’t there when you’re able to move again? Or perhaps you can’t see anyone, but have had a strong feeling that someone or something is really there? Have you heard loud and jarring noises just as you were nodding off, or seen a bright flash or bolt of lightning?


We caught up with sleep expert Prof Alice Gregory from Goldsmiths, University of London to find out more about these strange sleep phenomena…

What is exploding head syndrome and how common is it?

Exploding head syndrome involves the sensation of an explosion or loud noise when falling asleep or waking up. The experience might be similar to hearing the sound of a crash or a firework. While it can be alarming, it does not typically cause pain. The syndrome has been given this rather dramatic moniker, but some people, including one of our team, Dr Brian Sharpless, has been among those suggesting a new name: ‘episodic cranial sensory shocks’. This syndrome might sound frightening, but actually it is pretty common. For example, in one report 18 per cent of college students reported having experienced symptoms of exploding head syndrome.

What do we know about it?

There are many explanations for exploding head syndrome, but I won’t go into these. That’s because we want to know what people who have experienced these things think is going on, rather than what the experts believe might be happening.

Should I be worried if I have it?

Exploding head syndrome is considered to be pretty benign – and does not cause pain. However, some people have these experiences frequently and find them to be disturbing. If anyone is concerned, they should see a doctor who can rule out other disorders.

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What does this study seek to find out?

While exploding head syndrome is relatively common, we know little about it. For example, if someone is having these experiences and wants advice on how to stop them, there is little information we can provide. Certain techniques are said anecdotally to help but we lack the systematic studies to back this up.

So we want to add to our limited knowledge in this area. For example, we want to understand more about the associations between sleep habits, beliefs and exploding head syndrome. In particular, we want to know how people try to prevent these experiences from occurring or to disrupt them once they do occur – and which of these techniques are most successful.

What is sleep paralysis?

Sleep paralysis is another fascinating sleep phenomenon. It involves being unable to move just as we are falling asleep or waking up. It’s often accompanied by perceptions which aren’t there when movement returns.

How common is it, and what causes it?

Sleep paralysis is more common than one might expect. In one of our studies, roughly a third of our participants reported experiencing sleep paralysis at least once. In the same study we found that a number of factors were associated with sleep paralysis, but there’s a lot more to learn.

What do you want to find out?

As with exploding head syndrome, we want to understand more about people’s explanations for such experiences and also how people attempt to stop them from occurring or deal with them when they do so. One of our team (Prof Chris French) will also be building a database of those with sleep paralysis so that (with their permission) we can contact them about our future studies.

Why should I take part?

Nobody should feel obliged to take part. However, if you are interested in participating, we’d love to hear from you! Not only do we want to hear from those who have had these experiences, but we are just as interested in those who have not. We are keen to examine differences between those who have and have not had these experiences.

Who’s involved?

My own research over the years has primarily focused on sleep and mental health. I have only recently become interested in sleep paralysis and exploding head syndrome. My interest in these under-researched topics stemmed from fascinating discussions I had with Chris, who has been contacted by lots of people who reported these symptoms.

Chris also introduced me to Brian, who is a leading expert on both exploding head syndrome and sleep paralysis (and based at Argosy University, Northern Virginia). Together – and with help from a superb post-doctoral student, Dr Dan Denis, who is based at Harvard Medical School – we have developed a programme of research investigating these under-researched topics. Students at Goldsmiths, University of London, are also keen to get involved where possible too.

As with most research, this project is very much a collaborative effort. We hope that this project will not only result in interesting articles for BBC Focus magazine, but will produce data that will be publishable in scientific journals, and presented at conferences. It won’t happen without readers getting involved, so we are grateful for your interest in the study!

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