A drug often used to treat insomnia or difficulty falling asleep. It belongs to the class of sedatives and hypnotics and helps people with sleep disorders by changing certain molecules in the brain. The relatively rapid action of Lunesta is well known. Its purpose is to help people fall asleep quickly, which can be especially useful for people who have trouble falling asleep. Usually lasting just over a few weeks, Lunesta prescriptions are for temporary use only. This is beneficial because it reduces the likelihood of tolerance and dependence that can occur with other sleeping pills.