Ever since Colorado started getting high, crime has dropped by 10 per cent

The figures include the six months that recreational cannabis use has been legal in the state

A man smokes marijuana during the World Day for the Legalization of Marijuana in Medellin, Antioquia department, Colombia on May 3, 2014. (RAUL ARBOLEDA/AFP/Getty Images)

Crime in Denver, the capital of Colorado, has dropped by 10 per cent since last year - reassuring those who feared it would rise after the first legal marijuana stores opened in the state on 1 January.

The statistics published by Denver authorities show that crime overall dropped by 10.6 per cent, while violent crimes including sexual assault and homicide fell by about 5 per cent in total. Meanwhile, property crime such as motor theft fell by around 11 per cent in the city as a whole.

While the fall has not been directly linked to the legalisation of marijuana, the trend is likely to bolster pro-cannabis campaigners and those who welcome the $1.9million (£1.2 million) in tax the government has so far gathered from legal cannabis sales.

When medical marijuana stores are included, the Colorado collected $3.5 million (£2.1 million) in taxes since it became the first US state to legalise cannabis in 2012, with commercial sales beginning at the start of the year.

“All the naysayers who were against marijuana legalization are eating crow about now. Colorado’s weed sales just keep trending up, and with the sales of legal weed, they are improving their schools and reducing overall crime rates,” yoga teacher Christina Sarich wrote about the drop in crime in an article that has gone viral on pro-cannabis websites.

However, the latest figures coincide with the publication of a study by scientists from the University of Pennsylvania, who claim that marijuana can cause sleeping problems.

People who had taken the drug before they were 15 were twice as likely to suffer these complications, results showed.