The U.S. Food and Drug Administration (FDA) are requiring the manufacturer of the sleep drug Lunesta (eszopiclone) to lower the recommended starting dose.

Research suggests eszopiclone levels can remain high enough in the blood to impair activity through the morning after the dose was taken, an FDA Voice post reported.

This type of impairment could influence driving and other activities that require alertness

The recommended starting dose of Lunesta has been decreased from two milligrams to one. Users  are encouraged to contact their healthcare provider to find out what dose is best for them.

The FDA recommends that all sleep medication users should strive to take the lowest dose possible that still effectively treats their insomnia.

The dose change was spurred by a study of 91 healthy adults between the ages of 25 and 40. When compared with a placebo the drug was found to be associated with "morning psychomotor and memory impairment in both men and women 7.5 hours after taking the drug," the post reported.

The recommended dose could cause impairment to "driving skills, memory, and coordination" as long as 11 hours after the medication is taken.

Most of the patients in the study were not aware they were impaired.

The FDA approved changes to the Lunesta label. They also urged healthcare providers to warn their patients about the drugs impairing effects.

"Drowsiness is listed as a common side effect for all insomnia drugs, along with warnings that people may still feel drowsy the next day after taking one of these products. The FDA is continuing to evaluate the risk of impaired mental alertness with the entire class of sleep drugs, including over-the-counter drugs, and will update the public as new information becomes available," the post stated.

In 2011 the FDA also ordered a starting dose reduction in sleeping drugs with the active ingredient zolpidem.