What is Zopiclone? Seven people rushed to hospital in County Durham after taking sleep medication sparking fears of 'contaminated batch'

Cleveland Police said it had received reports on Friday (29 June) of the adults being taken to North Tees General Hospital in Stockton-on-Tees, County Durham. The incident has sparked fears of a "potentially contaminated batch".

The force is also investigating the death of one man believed to have taken Zopiclone. It said in a statement: "Officers are warning drug users of a potentially contaminated batch which could cause significant illness or lead to an overdose."

Zopiclone is usually used to treat severe insomnia, and takes around an hour to work. It helps users fall asleep faster and stop waking in the night. It works by triggering a calming chemical in the brain called gamma-aminobutyric acid (GABA), according to the NHS website.

The drug is only available on prescription and is usually taken as a tablet but doctors can order it in liquid form. The NHS warns against drinking alcohol after taking the drug because it can cause a "deep sleep where you find it difficult to wake up".

Users can become dependent on Zopiclone and it is prescribed for only two to four weeks because it becomes less effective as the body gets used to it.