What is "exploding head syndrome"

n. A rare parasomnia in which the subject experiences the auditory hallucination of a loud bang or similar noise inside the head.

Exploding head syndrome (EHS) is a benign condition in which a person hears loud imagined noises (such as a bomb exploding, a gunshot, or a cymbal crash) or experiences an explosive feeling when falling asleep or waking up. These noises have a sudden onset, are typically brief in duration, and are often jarring for the sufferer.

Exploding head syndrome is classified as a parasomnia and a sleep-related dissociative disorder by the 2005 International Classification of Sleep Disorders, and is an unusual type of auditory hallucination in that it occurs in people who are not fully awake. Neither the cause nor the mechanism of exploding head syndrome is known. As of 2015 there had not been sufficient studies conducted to make conclusive statements about prevalence nor who tends to suffer EHS. However, it has been previously thought that EHS was a rare syndrome, occurring primarily in older (i.e., 50+ years) individuals, females, and those suffering from sleep paralysis. However, a study in 2015 has shown that EHS affects more younger people than thought, reporting that nearly one in five of college students interviewed experienced EHS at least once. Statistics from the study did not show that EHS was more frequent in females, but instead found that more than one-third of those who had EHS also experienced isolated sleep paralysis. Furthermore, the study found that some subjects experienced exploding head syndrome to such a degree that it significantly impacted their lives.

Case reports of EHS have been published since at least 1876, which Silas Weir Mitchell described as "sensory discharges" in a patient. The phrase "exploding head syndrome" was coined in a 1920 report by the Welsh physician and psychiatrist Robert Armstrong-Jones. A detailed description of the syndrome was given by British neurologist John M. S. Pearce in 1989.