Zopiclone and eszopiclone (Lunesta) are the same compound — eszopiclone is the purified active stereoisomer of zopiclone. This 2026 guide covers the GABA mechanism, correct dosage by strength, why the metallic taste occurs, dependence and withdrawal risks, the next-day driving warning, complex sleep behaviour FDA boxed warning, and a full 4-Z-drug comparison table.