Office workers can become tetchy and depressed without a regular e-mail ‘fix’, research shows.

Internet service provider (ISP), intY, questioned its 10,000 users - and found more than half of them are happier after receiving emails.

The survey also revealed how a third of those questioned feel snappy and distressed if they don’t get as many emails as expected.

intY managing director Mark Herbert said: "It seems the 'You have mail' message has an almost narcotic effect on some users. Psychologically, being told you have mail has a soothing and affirming effect."