Exploding Head Syndrome, or the Bang That Never Happened
A harmless perception of a loud bang as you fall asleep or wake. In a 2015 study, 18% of 211 undergraduates had experienced it.
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At 1:50 a.m. a sound goes off inside the bedroom like a dropped tray of dishes. The sleeper sits up with a pounding heart. Nothing has fallen, nobody is in the hall, and the house is quiet.
That experience has a name: exploding head syndrome, a perception of a sudden loud noise (a bang, a crash, a gunshot) as a person falls asleep or wakes, with no sound in the room. The sensation is usually painless. People describe the noise, sometimes a flash of light, and a jolt of fear, and then it is over.
Who gets it, and how often?
The British neurologist J.M.S. Pearce coined the name in 1988 and described ten patients in 1989. For decades it was treated as rare and as something seen mostly in older patients. Brian Sharpless and Jeffrey Barber tested that in a 2015 paper in the Journal of Sleep Research, interviewing 211 undergraduates. Of them, 18.0% had had it at least once in their lives, and 16.6% had had recurrent episodes. About 37% of the students who had isolated sleep paralysis also had exploding head syndrome, so the two travel together more often than chance would give.
Sleep medicine classes it as a parasomnia, an unwanted event around sleep, the same family that holds the far more common talking in your sleep. The leading explanation is a glitch in the brain’s switch-off of sensory areas as sleep begins, so that a burst of auditory activity is felt as a real sound. That is a working theory, not a settled explanation.
How does it differ from its neighbours?
A hypnic jerk is a muscle twitch while dozing off. Sleep paralysis is being awake and unable to move. A hypnopompic hallucination is an image or voice experienced while waking. Exploding head syndrome is the noise-only one: loud, sudden, painless, over in seconds.
What helps?
For most people, the useful treatment is reassurance that it is harmless, since the fear and the disrupted sleep that follows tend to feed the next episode. Stress and sleep loss are commonly linked to bursts of it. A sudden, severe headache is another matter and should be checked promptly by a doctor.