Lunesta and Ambien are both used for insomnia. Ambien is better for people with trouble falling asleep (sleep-onset insomnia). This is because it acts quickly and doesn't stay in the body as long as other sleep medicines do. Lunesta is better for people who have trouble falling asleep and staying asleep (sleep-maintenance insomnia). It has a longer half-life in the body than Ambien, meaning it acts for a longer period. Lower doses of 1 to 2 mg help fall asleep, while higher doses of up to 3 mg are best for staying asleep.