True, the common cold is highly contagious—spurred by more than 100 viruses that are spread when inhaled or picked up from tainted surfaces and rubbed into an eye or the mouth or a nostril. But beyond frequent hand washing, there are a number of ways that people can raise their immunity:
1. Catch more zzzz's. A study published today in the Archives of Internal Medicine confirms what Mom has been saying all along: You need more sleep. After exposing healthy volunteers to a cold virus, researchers found that those who slept fewer than seven hours a night were about three times as likely to become ill as those who, on average, snoozed for eight hours or more. And even minor habitual sleep upsets (such as difficulty dozing off, or waking up throughout the night) had an impact; participants who lost just 2 to 8 percent of their total sleep time—that's about 10 to 38 minutes for an eight-hour sleeper—had nearly four times the risk of getting sick compared with those who fell asleep quickly and slept soundly.
"That's the really striking issue in this study," says Sheldon Cohen, the Carnegie Mellon University professor of psychology who led the new research, "that even relatively small disturbances in your sleep have a pretty big impact on your susceptibility to getting a cold." The ideal: falling asleep within 10 minutes of when head hits pillow.
2. De-stress. People under persistent stress, lasting a month or more, are more likely to get ill when exposed to cold viruses than people who aren't, according to Cohen's prior research. Marital strife, ongoing conflict with family members or friends, unemployment, having a job that's not commensurate with one's abilities—all seem to wear down resistance to colds, says Cohen, and the risk increases the longer these "stressors" last. A taxing day or week, for example, doesn't seem to make a difference. While Cohen admits that it's not so easy to defeat chronic stress, people might benefit from trying meditation, for example.
3. Expand your social life. Cohen's group has also found that people with diverse social networks—meaning they have lots of different types of social relationships—have better immunity to cold germs than those with narrow social circles. That's in line with a body of evidence showing that socially connected folks tend to live longer than those who are isolated, says Cohen. While some experts have argued that it's the quality of relationships, not the quantity of relationships, that counts, Cohen says his data indicate that these factors are pretty interchangeable. Mingling with more than, say, a spouse may do a body good.
4. Exercise. Aside from helping people stay fit, exercise has been shown to bolster the immune system, says William Schaffner, chair of the department of preventive medicine at Vanderbilt University School of Medicine and a spokesperson for the Infectious Diseases Society of America. Moreover, modest data suggest that exercise may actually help cold sufferers feel better quicker, he says.
5. Don't bother with echinacea. A 2005 study, published in the New England Journal of Medicine, found that echinacea extracts—three distinct preparations of the stuff—didn't keep participants exposed to a cold virus from becoming ill, nor did they help ease their symptoms compared with a placebo. "Those of us who are in medicine and public-health science think that question has now been put to rest," says Schaffner. While some herbal enthusiasts may argue that the study didn't cover every preparation or dosage, Schaffner considers the case closed: "I certainly am now quite convinced that echinacea is not useful in trying to prevent a cold."
6. A little vitamin C very likely won't hurt. Studies about the usefulness of vitamin C against colds "come down on both sides of the fence," says Schaffner. Helpful or not, there's probably little harm in taking the popular vitamin as long as people remember to keep hydrated, he says. Some people seem to think that if a little vitamin C is good, then taking a lot must be better, which isn't true. If a person is dehydrated, vitamin C can crystallize in the kidneys and bladder, creating stones.
7. Mom was probably wrong about wet hair in the wintertime. Does being wet and cold make people more vulnerable to colds? Probably not, says Schaffner.
In the end, while you can lower the odds of getting sick, the reality is that "you're going to get a cold anyway—it's a question of how many," says Aaron Glatt, president and CEO of New Island Hospital in New York and a spokesperson for the Infectious Diseases Society of America.