Scattered throughout past sleep research are a number of reports describing unusual behavior while sleepwalking, including sleep eating, sleep phone calls, sleep sex -- and even sleep rape and murder.
Now, a new case study is adding one more bizarre sleep phenomenon to the literature: sleep e-mailing.
In an article published in the journal Sleep Medicine, Seton Hall University researchers document the case of a 44-year-old woman who struggled with severe insomnia for years before she was prescribed the popular sleeping aid, zolpidem (also known by the brand name Ambien), in 2004.
The zolpidem helped with her insomnia at first, but the effects of the drug began to wear off after a period of time. Soon her doctor increased her dose, allowing her to get five hours of sleep per night.
But after starting this increased dose regimen, the woman received a puzzling phone call from a friend who said she was accepting her dinner invitation -- an invitation that she could not remember extending.
The woman's friend reminded her of the e-mail she'd sent the night before -- an e-mail of which the woman had no recollection. A search through her sent items folder recovered the following e-mail that she had apparently sent to her friend at 11:47 the previous night:
"I don't get it. Please explain Lucy! Come tomorrow and sort this hell hole out! Dinner and drinks, 4:00pm?Wine and caviar to bring only. Everything else, a guess?"
There were two other e-mails sent to her friend at 11:50 p.m. and 11:53 p.m., each of which seemed to be written in a strange language, full of capitalization errors and nonsensical phrases.
According to Dr. Fouzia Siddiqui, lead author of the case report and a neurologist at the University of Toledo, this particular sleepwalking case is unique; it is the first and only published case of "sleep e-mailing." But he says that it is even more notable for the amount of complex actions the woman had to take in order to compose these e-mails.
"Sleepwalking has occurred in the past where people will [conduct] other activities such as cooking or moving furniture around," Siddiqui said. "But this case is unique in that she wasn't just sleepwalking but doing things like turning on her computer, remembering her user name and password and typing entire e-mails."
Siddiqui said in this patient's case, the cause of her unusual sleepwalking episode was her increased zolpidem dosage. Siddiqui immediately reduced the patient's dose; since then, she has not had any episodes of sleepwalking.
Sleepwalking falls under the category of sleep disorders called parasomnia. Parasomnias are characterized by abnormal movements or behaviors that can occur in between sleep stages or from sleep arousal.
Studies on sleepwalking have found that somewhere between 5 percent and 10 percent of people are sleepwalkers.
Although this is the first case study reported on sleep e-mailing, Dr. Mark Mahowald, director of the Minnesota Regional Sleep Disorders Center at the University of Minnesota, said that he is no stranger to this phenomenon.
"Our group certainly has heard of e-mail sending and Web purchasing during sleepwalking," Mahowald said.
And while this phenomenon of sleep e-mailing is highly uncommon, most sleep experts agree that it is not so different from other types of sleepwalking episodes.
"This is no surprise, as sleepwalking is due to the a mixture of wakefulness and non-REM sleep -- resulting in enough wakefulness to result in complex behaviors [such as] sex, driving, walking, e-mailing and telephoning," Mahoney said.
"Sleep e-mailing is no different," said Dr. Karl Doghramji, medical director of the Jefferson Sleep Disorders Center at Thomas Jefferson University in Philadelphia. "It represents only a different behavioral manifestation of the same disorder."
But why do parasomnias occur in the first place? Some sleep experts have pointed in the past to a wide array of drugs designed to help us sleep. As more of these drugs hit the market, they say, reports of parasomnia have become ever more frequent and bizarre.
However, Dr. Donald Greenblatt, director of the Strong Sleep Disorders Center at the University of Rochester, says these cases of sleepwalking caused by a sleeping aid such as zolpidem are not nearly as common as most think.
"If you look at the number of times Ambien was dosed around the world since it came on market ... you'll see that this is fairly uncommon phenomenon compared to number of doses [prescribed]," Greenblatt said.
Greenblatt added that only about 5 percent of people taking zolpidem reported experiencing sleepwalking episodes as a side effect of the drug.
Because sleep aid drugs are psychoactive, Greenblatt explained, they are meant to turn off certain parts of your brain -- the effect of which could lead you to have a conversation or engage in activity that you will have no recollection of the next day.
Sleep experts said that if a patient experiences sleepwalking as a side effect of these medications, they should cease taking the drug and go to their doctor immediately.
But Greenblatt said the public fear of experiencing these sleepwalking episodes as a result of taking a sleep aid drug are unnecessary.
"Ambien is a very good drug -- a very effective hypnotic with few side effects, that's usually very well tolerated by people," he said. "We're seeing more reports about abnormal behavior in part because of the wide prescription of the drug and sometimes because of the less than responsible behavior on the part of patients taking the drugs."
Still, Dr. Frisca Yan-Go, director of the UCLA Sleep Disorder Center in Santa Monica, Calif., warned that patients should follow their doctor's advice when taking these medications.
"I tell my patients to try not to take sleep medication every day, allow at least eight hours of sleep before driving or operating machinery and do not use any alcohol or other sedatives with this medication," Yan-Go said.