A new study in the Archives of Internal Medicine shows Monday that anything less than seven to eight hours of solid sleep can lower your resistance to the common cold virus. [Xinhuanet Photo]

If you sleep short of seven hours a night, you're three times more likely to catch a cold. And if you sleep poorly, you're five times more susceptible to one as well.

A new study in the Archives of Internal Medicine shows Monday that anything less than seven to eight hours of solid sleep can lower your resistance to the common cold virus.

"Participants were interviewed daily over a two-week period, reporting how many hours they slept per night, what percentage of their time in bed was spent asleep (sleep efficiency) and whether they felt rested," said the study by Sheldon Cohen and colleagues at Carnegie Mellon University in Pittsburgh, Pennsylvania.

"The less an individual slept, the more likely he or she was to develop a cold," suggested their findings.

Cohen said the study supports the theory that sleep is important to immune function.

Cohen's team tested 153 healthy volunteers, locking them in a hotel for five days after infecting them with a cold virus.

The men and women who reported fewer than seven hours of sleep on average were 2.94 times more likely to develop sneezing, sore throat and other cold symptoms than those who reported getting eight or more hours of sleep each night.

Volunteers who spent less than 92 percent of their time in bed asleep were 5 and half times more likely to become ill than better sleepers, they found.

Sleep disturbance may affect immune system signaling chemicals called cytokines or histamines, the researchers said.

Meanwhile, Dr. David L. Katz, director of the Yale University School of Medicine Prevention Research Center, said the study highlights the importance of sleep in maintaining good health.

"Getting good sleep should count among the priorities of health-conscious people," Katz said. "Time invested in sleep will almost certainly be paid back in dividends of better health -- fewer colds and greater productivity."

7 tips on fighting off a cold

Also, to help enhance immune system and fight better against colds, doctors give out seven tips beyond merely frequent hand washing. They include:

1. Catch more zzzz's.

2. De-stress.

3. Expand your social life.

4. Exercise.

5. Don't bother with echinacea.

6. A little vitamin C very likely won't hurt.

7. Mom was probably wrong about wet hair in the wintertime.

(Agencies via Xinhua News Agency January 13, 2009)