Nearly 20,000 people visited an emergency room in 2010 after taking a popular sleep drug.
A new report by the Substance Abuse and Mental Health Services Administration finds adverse reactions to Zolpidem, the active ingredient in Ambien and other prescription sleep drugs.
Those reports of negative reactions went up more than 200 percent since 2005.
A majority of the patients who had problems were women and were over age 45.
Side effects include dizziness, hallucinations and drowsy driving but the effects can be significantly amplified if the drug is combined with anti-anxiety medications, pain relievers or alcohol.
In January the FDA told manufacturers of drugs that contain Zolpidem to cut the recommended dose in half for women and reduced the dose for men as well.