FDA: Cut Ambien Dosage for Women The agency is recommending slashing the sleeping pill dosage in half for women.

Jan. 10, 2013 -- The manufacturers of Ambien, Ambien CR, Zolpimist, Edluar, and other sleeping medications that contain the active ingredient zolpidem must lower their recommended doses for women, the U.S. Food and Drug Administration announced today.

The decision was driven by a series of clinical trials and driving simulation studies, which showed that zolpidem levels in women may be high enough to impair alertness in tasks after waking up, including driving.

The FDA is requiring new labels on medications that contain zolpiden and recommended that women currently taking sleeping medications containing zolpiden consult with their healthcare provider to determine if a lower dosage should be prescribed.

"The changes are different in women and men," Dr. Ellis Unger, a director in FDA's Office of Drug Evaluation, told ABCNews.com. "We don't understand why yet, but women are more susceptible to next-morning impairment."

ABC's Lisa Stark demonstrates the dangers of 'sleep-driving.'

Researchers found that after eight hours, a 10 mg dose of regular Ambien resulted in 15 percent of women and 3 percent of men having zolpiden levels high enough to cause next-morning impairment, which can negatively impact performance in tasks that require alertness, including driving.

With extended release prescriptions, such as a 12.5 mg dose of Ambien CR, the results were more similar between men and women but also more staggering. Researchers discovered zolpiden levels high enough to cause next-morning impairment in 33 percent of women and 25 percent of men.

Last year, ABC News correspondent Lisa Stark demonstrated the dangers of so-called sleep driving, that is driving after taking sleeping medication. See Story Here

The FDA recommends that women currently prescribed higher doses should continue taking their medications, but consult with their healthcare provider about cutting their dosage in half to reduce the risk of next-morning impairment.

"This announcement is at least a decade overdue," Diana Zuckerman, president of the National Research Center for Women & Families told ABCNews.com. "The FDA's announcement today will save lives, but the agency needs to do more to determine all the risks of Ambien and other sleeping pills."

The FDA today said that it is also examining the effects of other sleep medications, and will require companies to do driving studies to determine if different dosing is needed for those medications as well.

In response to the FDA announcement, Sanofi, the company that manufactures Ambien, issued a statement advocating for a continued dialogue with the agency on the matter:

"Sanofi stands behind the significant clinical data demonstrating the safety and efficacy of Ambien, which was FDA approved in the US in 1992, and the 20 years of real-world use and 22 billion nights of patient therapy worldwide. Ambien CR was approved in the US in 2005."

Drowsiness and next-morning impairment are widely known side effects from certain sleeping medications, but risks increase when individuals combine their doses with other drugs or alcohol, or sleep less than the recommended seven to eight hours.