Sometimes the most awful symptom can be entirely harmless. Such is the case with a rare condition called exploding head syndrome.
More than 55 cases have been reported in the medical literature, but it is likely that hundreds, if not thousands, of patients have experienced this phenomenon.
The condition is characterized by a terrifying sense of explosive noise in the head, and typically occurs within an hour or two after falling asleep. Individuals report that they are awakened by a startling and frightening massive sound that can be clearly distinguished from a dream. It occurs exclusively at night and is not accompanied by any pain.
Activities prior to retiring at bedtime do not appear to have any relationship to the sound, although three physicians who themselves suffered from these attacks reported that the incidents occurred during periods of personal stress or when they were particularly tired.
The attacks may develop at any time during life, even in childhood. Women are slightly more likely to experience these events than men. Sometimes two or more attacks may occur over a period of days or weeks, followed by total remission. Some individuals experience only one such attack during a lifetime. A family history of similar attacks has been reported by a few individuals, and some report a history of migraine or epilepsy. After the attack, patients often feel a sense of terror, rapid heartbeat, and anxiety.
No underlying cause has been identified to explain the condition, which was first reported in 1988. Some authorities have suggested that it may have something to do with a sudden movement of a middle ear component or a "springing open" of the eustachian tube. Others have suggested that it may be related to a minor seizure in the temporal lobe that contains the nerve cells for hearing.
All agree, however, that exploding head syndrome is an entirely benign condition, is not caused by psychological disturbances, but is very real and frightening.