The stress of returning to work on a Monday morning can trigger a dangerous increase in blood pressure, according to a Japanese study published in the American Journal of Hypertension and picked up by the BBC.
The Tokyo Women's Medical University study shows blood pressure readings on Mondays are higher than at any other time of the week, which may explain why deaths from heart attacks and strokes tend to peak on a Monday morning.
There are 20 per cent more heart attacks on Mondays than on any other day.
"Most people are free of the mental and physical burdens of work on a Sunday and experience a more stressful change from weekend leisure activities to work activities on Mondays," said Dr Shuogo Murakami, who led the research.
"There was a distinct peak on Mondays in this study."
Apparently volunteers who stayed asleep did not experience an increase in blood pressure - compelling evidence, if ever it were needed, of why we should all just stay in bed on Moday mornings.