British workers are suffering "e-mail stress" because they are swamped with messages and constantly monitoring their inboxes.
Staffers are left tired, frustrated and unproductive as they struggle to cope with a constant deluge of e-mails, researchers from Glasgow and Paisley universities in Scotland have found.
More than a third said they thought they checked their inboxes every 15 minutes and 64 percent said they looked more than once an hour.
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When researchers fitted monitors to their computers, workers were found to be viewing e-mails up to 40 times an hour.
About 33 percent said they felt stressed by the volume of e-mails and the need to reply quickly. A further 28 percent said they felt "driven" when they checked messages because of the pressure to respond.
Just 38 percent of workers were relaxed enough to wait a day or longer before replying.
Researchers found that many workers felt "invaded" by e-mails interrupting them as they tried to concentrate on their work. They felt pressured to switch applications to see whether the e-mails were urgent.
Female workers felt under greater pressure to respond than did men.
They concluded: "E-mail has become an indispensable tool in business. However, there is evidence that e-mail can exert a powerful hold over its users and that many computer users experience stress as a result of e-mail-related pressure."
Renaud said: "E-mail is the thing that now causes us the most problems in our working lives. It's an amazing tool, but it's got out of hand."