"A new class of sleep medications appears to help people fall asleep without causing grogginess the next day researchers say. These new medications  known as dual orexin receptor antagonists DORA  target a more specific region of the brain than popular sleep drugs such as Ambien and Lunesta promoting sleep without affecting learning and memory also called cognition according to the new research.  Weve shown that these compounds improve sleep at doses that dont impact cognition said Jason Uslaner lead author of a study published in the April  issue of Science Translational Medicine. Uslaner is director of In Vivo Pharmacology at Merck  Co. which funded the study.  Merck already has one such drug suvorexant under review by the U.S. Food and Drug Administration FDA.  More than  million Americans struggle to get a good nights sleep and about onethird of these use drugs to help the process the study authors pointed out.  But widely prescribed sleep medications such as Ambien zolpidem and Lunesta eszopiclone can leave people feeling hung over and inattentive the next day. So much so that the FDA recently cut recommended doses of Ambien and other drugs that contain zolpidem for fear that their use even the night before might impair driving or other activities the next day.  Lunesta and Ambien affect GABA receptors which are found throughout the brain and are associated with side effects including thinking disturbances and deficits in attention and memory explained Uslaner.  About  years ago scientists discovered chemical messengers known as orexins which are released by a relatively small brain region known as the lateral hypothalamus. This area of the brain releases orexins during the day to keep us awake and lowers levels at night so we can sleep.  The appeal of orexin antagonists said Dr. Michael Thorpy director of the SleepWake Disorders Center at Montefiore Medical Center in New York City is that they target a system thats more specific for sleep. That means theoretically fewer side effects and perhaps less of a tendency to be habit forming Thorpy explained.  Uslaner and his colleagues investigated a compound called DORA which has the same mechanism of action as suvorexant to see how it fared alongside not only Ambien and Lunesta but also diazepam Valium in rats and rhesus monkeys.  DORA did not lead to the same mental impairments as the other three drugs. Rhesus monkeys and rats performed just as well on memory and attention tasks shortly after being administered DORA as they did on an inactive placebo.  In each case the minimum dose to achieve sleep was compared with the minimum dose that altered memory and thinking. DORA promoted sleep at lower doses than those that impaired mental skills when compared with the control drugs.  This is the first time in years that scientists have targeted a totally different receptor in the quest to combat insomnia said Dr. Alexandre Abreu codirector of the UHealth Sleep Center at the University of Miami Miller School of Medicine.  But many questions remain Do the drugs truly have fewer side effects Will they be habit forming And will they change the quality of sleep in any way  Those questions will only be answered with more testing and use in humans he said.  Experts note that findings from animal studies do not always hold up in human trials.  More information  The U.S. National Institutes of Health http has more on insomnia.  SOURCES Jason Uslaner Ph.D. director In Vivo Pharmacology Merck  Co. Michael Thorpy M.D. director SleepWake Disorders Center Montefiore Medical Center New York City Alexandre Abreu M.D. codirector UHealth Sleep Center University of Miami Miller School of Medicine Miami Fla. April   Science Translational Medicine"