US authorities ordered sleep drug makers to lower their recommended dosage because evidence shows some people wake up groggy and not in the best shape to do things like drive.
The active ingredient to combat insomnia is called zolpidem and is contained in drugs like Ambien, Edluar and Zolpimist.
The order for labs to cut their recommended dosage came from the Food and Drug Administration.
It said new data showed zolpidem blood levels in some patients may be high enough the morning after people take them to hinder activities requiring maximum alertness, such as driving.
Ambien and another, longer-lasting version called Ambien CR are made by the French pharmaceutical group Sanofi. But there are 13 generic versions around the world, including Edluar and Zolpimist in the United States.
Women eliminate zolpidem from their bodies more slowly than men. So the FDA said it has advised manufacturers to lower the recommended dose for women.
The labeling should recommend that health care professionals consider a lower dose for men, the FDA said in a statement.
"To decrease the potential risk of impairment with all insomnia drugs, health care professionals should prescribe, and patients should take, the lowest dose capable of treating the patient's insomnia," said Ellis Unger, head of the FDA drug evaluation center.