Miami, United States | AFP | Monday 8/31/2015 - 19:00 GMT | 318 words

People who do not get enough sleep are four times more likely than their well-rested counterparts to catch a cold, US researchers said .

The findings in the journal Sleep are based on a study of 164 volunteers who allowed themselves to be exposed to the cold virus by researchers who were also tracking their sleep habits.

First, the subjects underwent health screenings and completed questionnaires so researchers could understand factors such as stress, temperament, and alcohol and cigarette use. 

Their sleep habits were measured for one week prior to the beginning of the study, which required them to stay in a hotel room in the Pittsburgh, Pennsylvania area.

Once sequestered in the hotel, researchers administered the cold virus via nasal drops and monitored the volunteers for a week, collecting daily mucus samples to see if the virus had taken hold.

The results showed that those who had slept less than six hours a night during the week leading up to the study were 4.2 times more likely to catch the cold compared to those who got more than seven hours of sleep.

Those who slept less than five hours were 4.5 times more likely to get sick.

"Short sleep was more important than any other factor in predicting subjects' likelihood of catching cold," said Aric Prather, assistant professor of psychiatry at the University of California, San Francisco, and lead author of the study.

"It didn't matter how old people were, their stress levels, their race, education or income. It didn't matter if they were a smoker. With all those things taken into account, statistically sleep still carried the day."

Previous studies have linked lack of sleep to chronic illness, premature death, susceptibility to disease, car crashes, industrial disasters and medical errors. 

One in five Americans gets less than six hours of sleep on the average work night, according to a 2013 survey by the National Sleep Foundation.