By Stephanie Stahl

PHILADELPHIA (CBS)— Federal health regulators have warned for years about the possible side effects linked to sleep medications. Now, the FDA has issued their strongest warnings so far, and it will impact millions of Americans who suffer from insomnia.

A prescription of Ambien will now come with a prominent warning on the box. The FDA is requiring labels and patient guides to alert consumers about possible side effects which doctors have known about for years.

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The agency is taking action after it found 66 cases of patients taking the drugs and engaging in activities that resulted in serious injury or death.

“They wake up for some reason during sleep and they exhibit behaviors we would perform while awake, like walking, eating, potentially even driving,” said Dr. Nancy Foldvary-Schaefer, from the Sleep Disorders Center at the Cleveland Clinic.

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Black box warnings are the FDA’s most prominent warning.

They will also apply to the popular sleep medications Lunesta and Sonata, alerting patients to the risk for potentially dangerous behaviors.

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“It may be that some people are genetically prone anyway to these kinds of disorders and the medication can become an additional trigger,” said Dr. Foldvary-Schaefer.

Doctors say the government’s warning is an important reminder that medication should not be the only tool for addressing insomnia.

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“Ten to 15% of adults in America have chronic disorder and being treated with these meds as a first-line therapy. When we know that other treatments, not medicine, but behavioral therapies, work as well, if not better, long-term,” said Dr. Foldvary-Schaefer.

Those therapies include relaxation techniques and creating a better sleep environment. While side effects from sleeping pills are rare, doctors say they can lead to serious injury.

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The FDA notes that not all sleep aids pose these risks and different people can have different reactions. It is estimated that more than 20 million people are using prescription sleeping pills.

Stephanie Stahl