Exploding head syndrome

Exploding Head Syndrome is a form of hypnagogic auditory hallucination and is a rare and relatively undocumented parasomnia event in which the subject experiences a loud bang in their head similar to a bomb exploding, a gun going off, a clash of cymbals, ringing, or any other form of loud, indecipherable noise that seems to originate from inside the head.

This noise usually happens at the onset of sleep or within an hour or two of falling asleep, but is not necessarily the result of a dream. Although the sound is perceived as extremely loud, it is usually not accompanied by pain. Attacks appear to change in number over time, with several attacks happening in a space of days or weeks, followed by months of remission. Sufferers often feel a sense of fear and anxiety before and after an attack, accompanied by elevated heart rate. Attacks may also be accompanied by perceived flashes of light (when perceived on their own, known as a "visual sleep start") or difficulty in breathing. The condition is also known as "auditory sleep starts". The associated symptoms are varied, but the benign nature of the condition is emphasized and neither extensive investigation nor treatment are indicated. Sufferers may experience an inability to vocalize any sound, or mild forms of sleep paralysis during an attack. There is no known treatment.

Causes
The cause of the Exploding Head Syndrome (EHS) is not known, though some physicians have reported a correlation with extreme fatigue. This condition has also been linked to rapid withdrawal from certain prescription drugs such as benzodiazepines and SSRIs. The condition may develop at any time during life and women suffer from it slightly more often than men. It is more common over the age of fifty, although it has been reported as young as age 10. Attacks can be one-time events, or can recur with attacks increasing or decreasing over time, sometimes with no incidents over long periods of time.

The mechanism is also not known, though possibilities have been suggested; one is that it may be the result of a sudden movement of a middle ear component or of the eustachian tube, another is that it may be the result of a form of minor seizure in the temporal lobe where the nerve cells for hearing are located. Electroencephalograms recorded during actual attacks show unusual activity only in some sufferers, and have ruled out epileptic seizures as a cause.

Related phenomena
These loud noises are a common feature of out-of-body experiences. In surveys, as many as 85% of respondents indicate perception of them during the onset of such experiences.

Symptoms
The Exploding Head Syndrome was first described in 1920 by the Welsh physician and psychiatrist Robert Armstrong-Jones. He characterized this condition as an exploding sensation in the head. Patients were awakened from their sleep by this event and the sensation persisted for several seconds. A detailed description of the syndrome was given by British neurologist John M. S. Pearce in 1989, who noted that it was most common in patients that were more than 50 years old.

Exploding Head Syndrome is a condition that causes the sufferer to occasionally experience a tremendously loud noise as originating from within his or her own head, usually described as the sound of an explosion, gunshot, door slamming, roar, waves crashing against rocks, loud voices, a ringing noise, the terrific bang on a tin tray, the sound of an electrical arcing (buzzing), or a thud. In some cases an instant flash of what is perceived as video "static" is reported both audibly and visually for a fraction of a second.

This syndrome can also cause the sufferer to feel an extreme rush or adrenaline kick going through his or her head, sometimes multiple times. In most cases, it occurs when they are in a state between asleep and awake. Some sufferers report familiarization with the subsequent fear or panic element such that they no longer consciously experience it.

In some cases repeated attacks lead to the sufferer gaining a fear of sleeping or resting, as this is the most common time for attacks to take place, and this can lead to the development of sleeping disorders such as insomnia.

In some cases it is isolated on the left side of the head, and seems to come from the inner ear region.

A few less common side effects include but are not limited to the following: Increased heavy breathing, loss of appetite and increased laughter.