Sleep, common sense, and the common cold

It's nice to be proved right every now and then.

Studies often poke holes in our long-held medical beliefs (see Sugar makes children hyperactive—and other medical myths). But every so often a study suggests that our instincts and observations are right on target.

One such study appeared recently in the Archives of Internal Medicine. Researchers looked at the commonly held notion that poor sleep makes people more susceptible to the common cold. The verdict? Those who slept longer were less likely to get sick when exposed to a cold virus.

The study included 153 adults who were paid $800 to be dosed with virus-fortified nose drops and kept under quarantine for five days. In the two previous weeks, they'd answered questions daily about how long they'd slept the night before, what percentage of their time in bed they'd been asleep (their sleep efficiency) and whether they felt rested.

Researchers found that people who slept less than seven hours a night were three times more likely to become ill than those who got at least eight hours of sleep. How deeply a person slept was even more important than how long. Those who spent less than 92 percent of their time in bed asleep were five and a half times more likely to become ill than those whose sleep efficiency was 98 percent or higher.

Although this type of study can't prove that poor sleep made people more likely to get sick when exposed to a cold, it does support what many of us have observed or intuited: that our resistance to colds is low if we aren't getting our Zzzs. So, chalk one up for common sense.

However, the study wasn't without surprises. Of particular note: how rested people felt didn't have any bearing on how likely they were to become ill.

What you need to know. The study's authors suggest that most adults should aim for between seven and eight hours of sleep a night, although individual needs vary. Of course, good sleep alone may not keep you from catching the latest bug that's going around. Make sure you also follow these preventive steps, which have stood the test of time and scientific study:

• If possible, avoid close contact with anyone who is ill.
• Wash your hands frequently and thoroughly.
• Avoid touching your mouth, nose and eyes.

And if you do become ill, experts say you're most likely to pass on a cold in the first two or three days that you have it.

—Sophie Ramsey, patient editor, BMJ Group

ConsumerReportsHealth.org has partnered with The BMJ Group to monitor the latest medical research and assess the evidence to help you decide which news you should use.

Read more about why you can't sleep, and how to get some sleep. And see our home remedies and Treatment Ratings (subscribers only) for the common cold.