Choosing a window seat on the plane increases the chance of deep vein thrombosis, it is claimed.
Research suggests those sitting by the window face double the risk of a potentially deadly blood clot. The dangers are even greater for obese passengers, who are six times more likely to develop a blockage than if they sit next to the aisle. One theory for this is that passengers find it easier to fall asleep by a window.
Sleeping for several hours at a time during long-haul flights is known to raise the chances of a blood clot. The problems come if the clot travels through the bloodstream to the lungs, where it can cause a pulmonary embolism.
In a report, the researchers from Leiden University Medical Centre in the Netherlands said: 'Passengers in a window seat had a two-fold increase in risk compared to those in an aisle seat, while there was no increase in risk in those in middle seats.
'One explanation may be that passengers are in a more cramped position in a window seat.'