Is Sleep More Important Than Fitness when Preventing Cancer?

I listened to a discussion on the radio this morning about a study by The National Cancer Institute. This study found that women who slept fewer than seven hours a day were more apt to get breast cancer. This finding took into account physical activity on the part of these women. In other words, according to this study if a woman got less than 7 hours of sleep (7 to 9 hours are optimum), no matter how much she worked out, the exercise negated the benefits of sleep in terms of risk for cancer! I was shocked and decided to delve into this topic when I got home.

In an article entitled Exercise plus sleep may lower cancer risk in women by Amanda MacMillin the radio information was coorborated. In essence if you don't get enough sleep your workouts may not work against cancer!

James McClain, Ph.D., the lead author of the study, is a fellow at The National Cancer Institute. Approximately 6,000 women were followed for close to 10 years. Over half of these women got cancer. The women who exercised the most lowered their rate of cancer by around 20%.

What is so important is that women who were getting some type of exercise, were younger than 65, and slept less than seven hours a night did not get the same positive results as those who got seven hours of sleep or more. It seems to me based on this study that if you have a choice of sleeping and exercising you want to sleep. I was a personal trainer so this information goes against my better judgment. I also am a sociologist who looks at studies. I have not seen McClain's complete study but it seems valid. McClain says that "Though this was a small study, it supports the hypothesis that sleep might modify the relationship between physical activity and cancer."

The reporter to whom I was listening said that those of us who take a nap during the day don't have to feel guilty anymore. The exact reasons for these findings are unclear. It's possible that if I sleep less my immune system won't work as well leading to cancer. It's possible that the reason I may not get a good night's sleep is because of an unknown condition I have which could lead to cancer. Hormones may also play a part in these findings.