Getting chilly can bring on a cold, British scientists said, overturning medical orthodoxy that says there is no connection between developing the viral infection and a drop in body temperature.
Researchers at Cardiff University's Common Cold Centre paid 90 students to sit for 20 minutes with their bare feet inbuckets of cold water.
The study found that 13 of the students reported cold symptoms, such as a runny nose or sore throat, compared with five in a control group of 90 students who kept their feet dry in socks and shoes.
"When you dip your feet into cold water, you cause a pronounced constriction to the blood vessels in the nose," said the centre's director Professor Ron Eccles.
"This is one of the factors we believe that actually can aid the virus by lowering the defences within the nose and triggering the symptomatic infection," he told the BBC.
Previous studies inoculated patients with the cold virus and then chilled them, but failed to find any link between temperature and catching a cold.
Eccles said his research differed by taking healthy people from the general population and then chilling them. "We believe that when common colds are circulating in the community, for every person who's actually got a cold there are two or three who are infected but haven't developed symptoms.
"And it's when you chill these people that you can convert a sub-clinical infection or symptom-free infection into a common cold with symptoms." The study, published in the journal Family Practice, found that the trial students developing cold symptoms also reported significantly more colds each year.
