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.
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."