LONDON, England -- Workers distracted by phone calls, e-mails and text messages suffer a greater loss of IQ than a person smoking marijuana, a British study shows.

The constant interruptions reduce productivity and leave people feeling tired and lethargic, according to a survey carried out by TNS Research and commissioned by Hewlett Packard.

The survey of 1,100 Britons showed:

• Almost two out three people check their electronic messages out of office hours and when on holiday
• Half of all workers respond to an e-mail within 60 minutes of receiving one
• One in five will break off from a business or social engagement to respond to a message.
• Nine out of 10 people thought colleagues who answered messages during face-to-face meetings were rude, while three out of 10 believed it was not only acceptable, but a sign of diligence and efficiency.

But the mental impact of trying to balance a steady inflow of messages with getting on with normal work took its toll, the UK's Press Association reported.

so basically, email makes you stupid, but watching TV makes you smarter?