Insomnia (sleep) drugs containing zolpidem, such as Ambien, have warnings that they may cause serious side effects. These side effects include: sleepiness during the day, not thinking clearly, sleep-walking, or doing other activities when you are asleep like eating, talking, having sex, or driving a car. Your health care provider should be notified right away if you find out that you have done any of these activities after taking zolpidem. These side effects are described in the FDA-approved patient medication guides that are required to be handed out each time a zolpidem product is dispensed.
In January 2013, the FDA announced a lowered dose for women taking zolpidem, as women eliminate the drug slower than men. Lowering the dose is expected to decrease both the risk of sleep-related behaviors and of next-morning impairment. The FDA recommends taking the lowest dose of your insomnia medicine that treats your symptoms. It is important to take insomnia medicine exactly as prescribed and to not take it when drinking alcohol.
Ambien medication guide: http://www.fda.gov/downloads/Drugs/DrugSafety/ucm085908.pdf
Dosage change announcement: http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm334798.htm