A recent survey conducted in London, found that e-mails hurt IQ more then smoking marijuana.

According to the TNS Research, the company who conducted the survey, the constant interruptions of e-mails reduce productivity, as reported by cnn.com.

The survey revealed that two out of three people check their e-mails while out of the office and on holiday’s according to cnn.com.

One of the highest reports in the study was that half of workers respond to their e-mail within 60 minutes of receiving one, as reported by cnn.com.

“This is a very real and widespread phenomenon,” Dr. Glenn Wilson said in an interview with cnn.com. “We have found that this obsession with looking at messages, if unchecked, will damage a worker’s performance by reducing their mental sharpness.”

Wilson a psychiatrist at King’s College London University conducted 80 clinical trials and monitored the workers throughout the day according to cnn.com.

The survey included 1,100 Britons.

As reported by cnn.com the IQ of individuals who attempted to juggle their workload as well as e-mail messages dropped 10 points. They also reported that this was double the four-point fall seen after smoking marijuana.

“The research suggests that we are in danger of being caught up in a 24-hour ‘always on’ society,” said David Smith of Hewlett Packard in an interview with cnn.com. “This is more worrying when you consider the potential impairment on performance and concentration for workers, and the consequent impact on businesses.”