The most common, short-term side effects of Lunesta include: Dry mouth. Unpleasant taste on the tongue, typically bitter or metallic. Drowsiness or difficulty waking up in the morning. Headache. Dizziness. Cold-like symptoms, such as runny nose or cough. Ongoing grogginess the next wfjga.usg: disturbing | Must include: disturbing. Sleep laboratory studies of the effects of eszopiclone have confirmed the drug's clinical The most common side-effects were unpleasant or bitter taste, headache, or aggravated by another sleep disorder, a disturbance of circadian rhythm. Mar 15, - Ambien and Lunesta are among the 13 sleep medications that the reports of the unusual side effects have grown as use of sleeping pills has increased. binge eating and — most troubling of all — driving while asleep.