(IOWA CITY, Iowa) -- On Tuesday's World News broadcast, correspondent Lisa Stark demonstrates the dangers of driving after taking sleeping medication. She traveled to the University of Iowa, home of the most advanced driving simulator in the country, to reproduce the experience of driving while under the influence of such medication.
Watch the driving simulation experiment:
Although the term "sleep driving" has been used to describe impaired driving due to misuse or abuse of sedative drugs like sleeping pills, the term technically refers only to cases when individuals drive while actually asleep or not fully conscious -- much like sleep walking. These individuals typically drive in an impaired or unsafe manner.
First reported in 1996, sleep driving falls under the category of "complex behaviors" that can be side effects of certain sleeping pills. Other reported complex behaviors include sleep eating, sleep sex and sleep violence.
Such complex behaviors, however, are actually quite rare. In a review from 1992-2006 reports, researchers found a total of only 14 reports of sleep driving.
A much more common concern of sleep medications is impaired driving due to misuse of these drugs. In 1999-2005, a study found that zolpidem, a common sleep medication that also is manufactured under the name Ambien, was the major intoxicant in 187 of 8,121 DUI arrests in Wisconsin -- in other words, 2.3 percent. The DUI arrests occurred at all times of the day and night, with nearly a quarter of them occurring between 8:00 a.m. and noon.
"A good safe medication that can quickly get you to sleep is on the market, but if you take it at the wrong time, that's the problem," says Dr. Mark Eric Dyken, director of sleep disorder center at the University of Iowa. "If you take it when you're supposed to be awake…it's gonna be dangerous."
This danger persists if people drive too soon after taking the drug. Package inserts on sleeping medication recommend at least seven to eight hours of sleep before engaging in activities such as driving. Because the half-life of zolpidem, for example, is 2.5 hours -- meaning 50 percent of the drug is eliminated from the body every 2.5 hours -- it should take about seven to eight hours for most of the drug's effects to leave the system. At this rate, about 97 percent of the drug is out of a person's system 12.5 hours after they take it.
The pill's developer, Sanofi-Aventis, says it stands behind the safety and efficacy of Ambien when used as directed, and there is a clear warning on the drug label that patients should receive seven or eight hours asleep before being active.
Despite this, many people may be driving before the drug is out of their system. In an American study conducted by National Highway Traffic Safety Administration, zolpidem was found in 0.12 percent of daytime drivers and 0.01 percent in nighttime drivers. In a similar survey in Norway, where hours of daylight can be extremely long or short and many people use sleeping medication to manage sleep schedules, levels of a sleeping medication called zopiclone was found in 2.3 percent of drivers during weekdays and 1.9 percent on weekends.
This dangerous trend of drivers under the influence may continue, as the market itself has grown 13 percent over the last four years, to 60 million total prescriptions written for all sleep medications in 2011, contributing to a $1.6 billion market. Popular sleeping drugs include zolpidem, as well as eszopiclone (Lunesta), temazepam (Restoril) and triazolam (Halcion).
Since its approval in 1992 for the treatment of insomnia, zolpidem has been the best-selling sleep medication -- a trend that continues to climb. Prescriptions for all forms of zolpidem have increased in 29.8 percent from 2007 to 2011, with 44.8 million prescriptions written in 2011, 95 percent of which are for the generic version.
This increase in sleeping pill popularity should be tempered with the knowledge of their side effects. In 1995, the U.S. Food and Drug Administration changed the labeling of zolpidem to include warnings that the drug could increase the risk of depression or suicidal thinking. A 2008 revision of these warnings added complex behaviors, including sleep driving and hallucinations, to the label.
Patients should also exercise caution to obtain at least the recommended amount of sleep -- seven to eight hours -- after taking sleeping pills. Any less sleep, and patients may exhibit the types of impairment that are common to sleepy drivers: poor or slow coordination, nystagmus (rapid back and forth eye movement), lack of balance, poor performance on sobriety tests, slow or slurred speech, muscle flaccidity, impaired vision, drowsy, tired, confused, disoriented appearance, and short term memory loss.
ABC News' Stark had been a great example of what happens after taking a sleep medication and driving. After three drives, she reviewed her experience, recounting her memory of two of her drives while on the medication.
"But you actually had three drives while you were on the Ambien," simulator research director Chrysler told her.
"I had three drives?" she asks. "Are you sure?"
"Yes," Chrysler confirms. "You were so asleep when we stopped that we had to wake you up in the driver's seat to get you out of the car."
"Well, I don't remember that many drives," says Stark. "I don't remember that many drives so clearly. One of them at least is a blur."
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