Individuals with exploding head syndrome hear or experience loud imagined noises as they are falling asleep or waking up. In his article, "Clinical features of the exploding head syndrome," J. M. Pearce asked individuals with exploding head syndrome to describe what noises they commonly heard during an episode. Examples included a loud bang, explosion, shot gun, thunderclap, loud metallic noise, firecrackers, and "noise as if head will burst open". Because the sound seems to occur abruptly and with apparently great force, patients may be so alarmed that they may initially and inaccurately describe the noise as pain. In fact, in a clinical study, some patients reported the sound as an "enormous roar, so loud it could kill me". However, upon closer questioning in several studies, there is no pain associated with the syndrome. It is important to note that in some cases, some subjects reported that the sound was mild.[10]
In addition to noise, some people report fear, distress, confusion, myoclonic jerks, tachycardia, sweating, tinnitus, simultaneously seeing flashes of light, and the sensation that felt as if they had stopped breathing and had to make a deliberate effort to breathe again.
The pattern of these auditory hallucinations is variable. Some patients report having a total of two or four attacks followed by a prolonged or total remission, having attacks over the course of a few weeks or months before the attacks spontaneously disappear, or the attacks may even recur irregularly every few days, weeks, or months for much of a lifetime. Furthermore, some patients reported having up to seven EHS attacks throughout the night.