Hello. Welcome to Healthcare Magic. I'm Dr. Christensen.
It sounds like you may have developed a cardiac dysrhythmia
(an irregular heartbeat). It's unlikely your zopiclone
has anything to do with this problem, as cardiac side effects aren't common with this medication. Cardiac dysrhythmias can stem from isolated electrical problems in the heart's conduction system -- a "short circuit," if you will -- or they can arise from irritability in the heart due to underlying coronary artery
disease. Atrial fibrillation
is the most common sustained cardiac dysrhythmia, but there are others.
Some over-the-counter medications, such as No-Doz and nonsteroidal anti-inflammatories, can trigger dysrhythmias, as can stress, sleep deprivation
In any event, this is a situation that warrants a medical evaluation, and I would suggest you see your doctor as soon as possible.
I hope things go well!