Diane Mapes writes:

Marie Raymond sometimes wakes up in the middle of the night, heart pounding, freaked out by the sound of her name being shouted loud and clear. Other times she'll be awakened by the sound of a huge crash, as if someone has broken a window or knocked over a set of dishes. 

"The sound is terrifying — super loud, like someone has broken in," says Raymond, a 38-year-old arts administrator from Seattle. "But when I get up to look around, nothing's amiss and everything's quiet." After dealing with it off and on for the last several months, Raymond believes she may have exploding head syndrome. She hasn't seen a doctor about it, but has done some research online.

As strange as the name sounds, exploding head syndrome is actually a rare and relatively undocumented sleep phenomenon. While sleeping or dozing, a person with the condition hears a terrifically loud sound in their head, such as a bomb exploding, a clash of cymbals or a gun going off.

"It's usually described as a loud bang or pop that occurs in the first third of the night," says Dr. Neil Kline, sleep physician and representative of the American Sleep Association in Wilmington, Del. "It's a sensory phenomenon. The individual senses that some type of explosion has occurred nearby, but ultimately realizes it's in their head. It's not associated with pain or with any disorder that we know of and there are no physiological medical consequences that are associated with it."

Thought to be brought on by anxiety or extreme fatigue and occurring in clusters during stressful periods, exploding head syndrome is not dangerous, according to the American Sleep Association Web site.

It can be disconcerting, though, stirring up images of a David Cronenberg movie. "Individuals can develop an aversion to falling asleep," says Kline. "They'll develop insomnia because they're concerned by these occurrences. But they're usually rare. I've never heard of it occurring regularly."

First described in 1920 as a "snapping of the brain," there is little to be found on the phenomenon in medical literature. Some patients experience a bright flash of light along with the loud explosion or crash, according to a 1989 study in the Journal of Neurology, Neurosurgery and Psychiatry that looked at 50 patients suffering from the syndrome. In almost every case there are physical aftereffects, such as "a sense of alarm, together with a cold sweat, labored breathing and tachycardia" (a rapid heart rate).

Or as Raymond puts it, you suddenly wake up "feeling like a character out of Poe."

As for the explosions themselves, patients have described them as a shotgun blast, a thunderclap, a loud metallic noise, the clash of cymbals, a lightning strike or the sound of every door in the house slamming. Luckily, the crash, bang, or boom lasts only a few seconds and disappears as soon as the person awakens. Episodes, which are usually clustered over the course of a few days, will then disappear for months — or years — on end.

It's unclear why stress would bring on a crashing sound in your head, although some have speculated that it may be the result of a movement of the middle ear component or of the eustachian tube.

J.M.S. Pearce, the British neurologist who coined the term, calls it a "mystery" requiring further study. He also felt the phenomenon was not as rare as some believe, perhaps due to people's hesitancy to discuss it. "Many [patients] said they had been ashamed to mention it to their doctors or that their complaint had been greeted with incredulity if not frank disbelief," he wrote in his 1989 study "Clinical features of the exploding head syndrome."  "It is entirely benign, and I suspect quite common, but underreported."

Exploding head syndrome is said to happen more often after the age of 50 (although there have been reports of it happening in children) and believed to be more common among women. Due to the rarity of the syndrome, though, it's hard to establish any kind of parameters, says Kline.

"I'm not convinced there's good data that describes the demographic of this phenomenon," he says. "I've only had a few patients during my career who have described it and no one has ever asked to be treated for it."

Since the phenomenon is often linked to stress, sleep experts suggest relaxation techniques  like exercise, reading before bedtime or yoga to help alleviate the episodes. According to studies, a few patients have also found relief by taking certain types of antidepressants. A 2001 study in the journal Current Pain and Headache Reports found "most sufferers require only reassurance that the spells are benign in nature." 

But hearing a sudden loud banging in the middle of the night can be very frightening. "So if an individual is experiencing this and it's disrupting their sleep or causing them anxiety, they should talk to their doctor about it," Kline advises.

Despite the sensational name, there's no danger that your head will actually blow apart.
"When most people hear of it, they visualize an individual's head exploding," says Kline That's not what happens."

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Brian Alexander writes:

The aliens in "Avatar" may be blue, but some moviegoers feel green after watching it.

The stunning 3-D technology featured in "Avatar" is undoubtedly crucial to the sci-fi epic's nine Academy Award nominations (including Best Picture) and speedy rise to become the world's highest-grossing film worldwide. But despite its phenomenal popularity, not everybody has "3-D ready" eyes. A big group of people around the world have reported feeling nausea, dizziness and other ill effects while watching the film in 3-D. Others are stereoblind, that is, they don't see properly out of both eyes – or are missing an eye, because of cancer, say — and can't enjoy the effects of the state-of-the-art digital technology.

And if you got sick during "Avatar," forget about going to see the 3-D versions of "Alice in Wonderland" (opening on March 5), "Clash of the Titans" or the next "Harry Potter" movies.

A variety of visual and neurological conditions can cause someone to experience nausea and headache while watching a movie in 3-D, especially a group of disorders related to the body's vestibular system — the network of nerves, fluids and canals in the ear that connect to the brain and help us keep our balance and orient ourselves in space. About 35 to 40 percent of adults over age 40 have some sort of vestibular problems, according to Lisa Haven, executive director of the Vestibular Disorders Association, who says she has trouble herself. She hasn't seen "Avatar." "I think about it with trepidation," she said.

But even younger folks who have never been diagnosed with a dysfunction in the inner ear could experience a kind of motion sickness while watching 3-D, experts say.

A 3-D image creates an illusion of depth when the brain fuses two, slightly different 2-D images as they are projected on the movie screen, one perceived by each eye. This is called binocular disparity.

We need 3-D glasses to provide each eye with its version of the image. The glasses are worn very close to our eyes and the lenses of our eyes want to focus on this close-in image, but the binocular disparity is telling our brains that the image is further away.

Two researchers, Frederick Bonato and Andrea Bubka of St. Peter's College in Jersey City, N.J. call the problem "sensory conflict."  Because our eyes are central to helping our vestibular system keep us oriented (try spinning with your eyes closed), the conflict creates confusion and "the brain can be tricked into thinking the body has been poisoned," says Bonato, editor-in-chief of the journal Aviation, Space and Environmental Medicine.

That may sound off the wall, but when we are poisoned we often get nauseous so we can expel whatever is poisoning us. Of course, the 3-D technology isn't literally poisoning us, but the conflicting sensory input can seem similar to the effects of, say, bad mushrooms, and so our brain communicates along the vagus nerve and tells us to throw up.
 
Bubka felt this effect for herself when she went to Avatar. "We both saw Avatar and I felt a little sick, though Frederick did not," she said. "There is a lot of variability among people."

Diseases like multiple sclerosis, and Meniere's Disease (which appears to have several possible causes) and something called BPPV or benign paroxysmal positional vertigo – which can be caused by ear infections, trauma, toxins and other insults – are common reasons why people suffer from vestibular dysfunction.

Others are sharing their problems relating to Hollywood's 3-D juggernaut. "My friends and I all went and saw Avatar," one poster on a SomethingAwful.com forum wrote. "During the movie my eyes felt like they were going to pop and my head was splitting and I felt a little sick. During the movie about 15 people walked out."

Many people do learn to compensate for inner ear problems by relying on their eyes and their neuromuscular system to feed accurate information to the brain. But when the eyes are being fed conflicting information by 3-D, they can't, explained Patricia A. Winkler, professor emeritus at Regis University in Denver and a clinician who works with people suffering from vestibular dysfunction.

"So you are sitting in a movie theater, sitting still, and your muscles say 'No, you are not moving,'" she explained. "And your inner ear system says there's no fluid movement. But your visual system says 'Lots of things are moving out there and in 3-D' like what you see in everyday life. That's powerful because that 3-D flow on your retina tells you 'Yes, I am moving' and it is easy to believe your visual system because in humans, that is a high priority sensory system."

In other words, it's like getting carsick or seasick in a movie theater. There are rehabilitative therapies for extreme cases of vestibular dysfunction that can help those at risk for frequent falls, broken bones, and difficulties driving, for example. But for those with milder cases, the best solution for 3-D movie queasiness may be to stick with the 2-D version.

At least then you won't have to spend two hours wearing goofy glasses.  

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