The millions of Americans who use sleep drugs were warned last week by the U.S. Food and Drug Administration to talk to their doctor about lowering the dosage of a commonly used type of insomnia drug in hopes that less of the drug will be in the bloodstream the next morning when the person gets behind the wheel to drive somewhere.

IMS Health, a health care technology and information company with an office in Plymouth Meeting, said about 60 million prescriptions were written for all sleeping pills in 2011, with about two thirds of those being some form of zolpidem. The drug is sold as a generic and under the brand names Ambien, Ambien CR, Edluar and Zolpimist.

"Over the years FDA has received spontaneous adverse event reports of driving impairment and motor vehicle accidents associated with zolpidem, but these reports lacked the information necessary to fully understand whether and how zolpidem affected people's mental alertness and ability to drive," Dr. Ellis Unger, a director in the FDA's Center for Drug Evaluation and Research said in a statement. "Recently, data from clinical trials and other types of studies have become available, which allowed FDA to better characterize the risk of next-morning impairment."

The FDA statement is here.

One of the interesting things to spin out of the FDA teleconference with reporters was that Unger said the FDA would greatly expand its use of driver simulation testing for sleep medication. But that testing aspect might eventually also apply to other drugs that would impair drivers.

The University of Iowa's National Advanced Driving Simulator says recently got a $650,000 research contract from the National Highway Traffic Safety Administration to research ways of detecting drowsy, distracted, and alcohol-impaired driving.

A link to the NADS web site is here.

Omar Ahmad, director of operations for the NADS, said this field of testing is going to expand. Critics will argue that any subject involved in testing will know that it is a simulation, but differences between how the subject functions with and without a substance can be distinguished.

"We have researchers at Iowa looking not just at sleep drugs, but testing protocols for entire classes of drugs," Ahmad said. "Researchers looking at the relationship and effects of CNS - central nervous system - drugs and whether they can affect people when they drive."

But science and testing can take a long time to eventually arrive at simple messages, so Ahmad offered a good one.

"If I can offer a public service message here," Ahmad said, "we as individuals, really any person using a drug, needs to talk with their doctor about when and how a drug might affect their ability to drive, or a combination of drugs. Not that a doctor can be fully aware of all the combinations, but asking the questions, having the conversations, would be a good first step."