The U.S. Food and Drug Administration announced on Thursday that it will require manufacturers of several insomnia drugs, including the popular Ambien, to lower their recommended doses.

According to a statement from the federal agency, medications such as Ambien, Edluar and Zolpimist all contain an active ingredient called zolpidem that induces drowsiness in patients. However, the FDA has found that many prescribed users of the drugs still have high amounts of zolpidem in their systems after waking up, making daily activities like driving much more dangerous.

To combat this impairment of activities that require high levels of alertness, the FDA has recommended that any drug using zolpidem as an active ingredient must have lower suggested doses. According to the agency, “Using lower doses of zolpidem means less of the drug will remain in the blood in the morning hours.”

One big issue for the drugmakers, however, is the fact that men and women metabolize zolpidem at different rates. This means that women often have higher residues of zolpidem in their systems the morning after taking Ambien than men do.

To address this, the FDA suggests that suggested dosages of drugs like Ambien be cut in half for women, while men should consult their doctors about a proper dosage for them, though the lower doses are still recommended.

“Patients should also read the medication guides and understand the benefits and risks of these drugs,” Dr. Ellis Unger of the FDA’s Center for Drug Evaluation and Research said. “We believe that by lowering these doses, we can decrease the side effects that happen the morning after.”

While the FDA recommends lowering suggested dosages, it also suggests that anyone currently on drugs such as Ambien or Edluar consult their doctors before changing doses on thir own.

“Over the years the 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,” said Unger. “Recently, data from clinical trials and other types of studies have become available, which allowed the FDA to better characterize the risk of next-morning impairment.”

Vermont Public Radio notes that in 2011, more than 40 million prescriptions were issued for drugs containing zolpidem, making Ambien and similar drugs the most widely used insomia drugs in the country.