The U.S. Food and Drug Administration released a statement Thursday regarding the decision to require relabeling of the sleep aid Lunesta that will recommend a starting dose of half the amount it had been before the decision. The decision was based on research indicating that levels of eszopiclone, the generic name for Lunesta, after a full night’s sleep were still sufficiently high enough in some patients to impair driving and other activities that require full wakefulness and altertness. Lunesta is marketed by Sunovion Pharmaceuticals, Inc.

The new labeling will recommend taking one milligram instead of two at bedtime for both men and women. Users may increase their dose to two or three miligrams, as needed, but impairment may linger into the next day. The new recommended starting dose results in less drug in the body by morning, reducing the risk of impairment.

The statement advised patients currently taking doses higher than one milligram to consult with their health care professional for instructions on how to adjust their doses, if necessary.

“To help ensure patient safety, health care professionals should prescribe, and patients should take, the lowest dose of a sleep medicine that effectively treats their insomnia,” said director Ellis Unger, M.D. of the  Office of Drug Evaluation I in the FDA’s Center for Drug Evaluation and Research. “Recently, data from clinical trials and other types of studies have become available, which allowed the FDA to better characterize the risk of next-morning impairment with sleep drugs.”

Side effects of Lunesta include drowsiness, including drowsiness the next day. The FDA has ongoing evaluations of the risk of impaired mental alertness with all sleep drugs, both prescription and over-the-counter. This is not the first relabeling of sleep drugs to reduce next day mental alertness impairment. In January 2013, the FDA reduced the dose of drugs such as Ambien and Ambien CR that contain zolpidem.