Workers distracted by email and phone calls suffer a fall in IQ more than twice that found in marijuana smokers, new research has claimed.
Many workers are always on standby to react to incoming messages
The study for computing firm Hewlett Packard warned of a rise in "infomania", with people becoming addicted to email and text messages.
Researchers found 62% of people checked work messages at home or on holiday.
The firm said new technology can help productivity, but users must learn to switch computers and phones off.
The study, carried out at the Institute of Psychiatry, found excessive use of technology reduced workers' intelligence.
Those distracted by incoming email and phone calls saw a 10-point fall in their IQ - more than twice that found in studies of the impact of smoking marijuana, said researchers.
More than half of the 1,100 respondents said they always responded to an email "immediately" or as soon as possible, with 21% admitting they would interrupt a meeting to do so.
The University of London psychologist who carried out the study, Dr Glenn Wilson, told the Daily Mail that unchecked infomania could reduce workers' mental sharpness.
Those who are constantly breaking away from tasks to react to email or text messages suffer similar effects on the mind as losing a night's sleep, he said.