Does sleep protect against cancer?

We all know the short-term effects of not getting enough sleep, whether it's on our ability to concentrate or on the bags under our eyes. But sleep loss is more than a short-term problem. New research shows that regularly sleeping for less than six hours a night can increase your chances of heart disease, stroke, and colon cancer.

There's been research before linking sleep deprivation to heart and circulation problems. That's probably because lack of sleep seems to disrupt hormones, blood pressure, and blood sugar, as well as being linked to weight gain and obesity. The latest study summarized the results of earlier research, to produce a figure of a 50 percent increased chance of heart disease, and a small increase in stroke risk.

But this is the first time that lack of sleep has been linked to increased cancer risk. This study asked people being screened for colon cancer with a colonoscopy to fill in a questionnaire about their sleep. Those who were found to have adenomas (small growths that can turn cancerous, also known as polyps) were more likely to report regularly sleeping less than six hours a night. Compared to the folks who slept a good seven to eight hours, their risk of adenoma was up 50 percent.

Should we worry? Well, when Consumer Reports surveyed Americans about their sleep a couple of years ago, half said they had problems either falling asleep, waking during the night, or awakening much too early in the morning. That's a lot of people increasing their risk of serious illness.

Curiously, too much sleep may not be good either. The study looking at heart disease and stroke found the risk went up for people sleeping more than about eight to nine hours a night, too. The optimum sleep time seems to be seven to eight hours.

What you need to know. If you're having trouble sleeping, there's plenty you can do to give yourself a better chance of a good night's sleep:

• Avoid eating a large meal just before you go to bed.
• Avoid tobacco and drinks that contain caffeine or alcohol for a few hours before bedtime. 
• Go to bed only when you feel sleepy, and not just because you think it's time for bed.
• Use the bedroom just for sleeping and having sex. Don't use it to read, watch television, eat, or work.
• Try to keep your room cool and quiet.

To find out more, see our information on insomnia.

—Anna Sayburn, 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.