Tox Tuesdays: Zopiclone

People have been using sleep aids for hundreds of years. However, as with most things, moderation is vital.

In recent years, zopiclone has become one of the most preferred ways to treat short-term sleep disorders. When used properly, the levels of zopiclone that remain in the bloodstream typically are minimal after eight hours of sleep1. However, these drugs can be abused and with severe consequences for the person taking the drug and others, especially if that person gets behind the wheel of a car.

In addition to inducing sleep, zopiclone also affects cognitive function, such as impaired memory and reasoning, along with reduced coordination. Most overdoses from zopiclone occur after it is taken with other drugs, including alcohol2, according to a report from Lifelinea drug and alcohol charity.

Approximately 3 to 7 percent of the adult population in the U.S. and Europe uses either zopiclone or zolpidem (a similar drug) to combat insomnia. However, in a 2009 study that looked at the link between the two drugs and impaired drivers, zopiclone showed a significant link between the amount of drug in the drivers’ system and impairment (this correlation wasn’t seen with zolpidem)3according to Gustavsen et al.

Likewise, drivers who had ingested alcohol showed a similar correlation to those who had ingested zopiclone – that is, the more they ingested, the greater the impairment.

“Zopiclone and zolpidem are usually used in moderate amounts before bedtime, and will often be excreted from the body by the next morning. There are few users of these hypnotics that are stopped by police based on suspicion of driving under the influence,” said Ingebjørg Gustavsen of the Division for Forensic Toxicology and Drug Research in Science Daily. “In the meantime, we know that these substances also have abuse potential, as do other sedative or sleep-inducing medicines. Over 90 percent of the drivers included in the study because of zopiclone /zolpidem-use had higher concentrations of the substances in the blood than one would expect from normal therapeutic use of sleeping tablets before bedtime.”

Studies have shown zopiclone is an effective and safe method for treating insomnia when taken as prescribed on a short-term basis. However, long-term use has shown an increased risk of dependence4.

1 Jones, A. W., & Holmgren, A. (2012). Concentrations of zolpidem and zopiclone in venous blood samples from impaired drivers compared with femoral blood from forensic autopsiesForensic Science International222, 118-123.

2 Newcombe, R. (2009). Zopiclone: Assessment of the consumption and consequences of zopiclone (zimovane) among drug-takers in a north-east townLifeline Project, Retrieved from

3 Gustavsen, I., Al-Sammurraie, M., Mørland, J., & Bramnessc, J. G. (2009). Impairment related to blood drug concentrations of zopiclone and zolpidem compared to alcohol in apprehended driversAccident Analysis and Prevention41, 462-466.

Jones, I. R., & Sullivan, G. (1998). Physical dependence on zopiclone: case reportsBMJ316, 117. doi:

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