Conventional wisdom that Monday is the most miserable day of the week has been turned on its head by researchers, who have found that Tuesday is when most people are at their lowest ebb.
Researchers at the London School of Economics have been onitoring the moodswings of 22,000 people, reports the elegraph.
Over a two-month period volunteers have been registering their state of mind with the help of an iPhone application called Mappiness,
"It seems plausible that on Monday the weekend has not quite worn off," said George MacKerron, of LSE's Department of Geography and Environment, who is running the project.
"By Tuesday they are well into the working week and the following weekend is not yet in sight," he said.
The information has been gathered by sending an alert to volunteers' iPhones twice a day.
They are asked how they feel, who they are with, whether they are at home and what they are doing.
Their exact position is logged at the same time by satellite - using the same technology as employed in car navigation systems.
This also enabled researchers to discover the happiest - and indeed unhappiest - places in the country.
Thus far Bournemouth is the happiest place in the country, with 82 per cent of respondents seeming pretty content.
Life is rather less cheerful in the City of London, Eastbourne and Slough, where the Office comedy series was set.