According to a new study led by James McClain of the National Cancer Institute, practicing regular physical activity can significantly reduce the risk of cancer among women but only if the hours of sleep are not reduced. In other words young people who sleep less than seven hours a night are at risk of being diagnosed with cancer 47% higher than those who sleep well.

“We think it’s quite interesting and intriguing. It’s kind of a first look into this. It isn’t something that has been widely studied,” explained the study’s principal author, James McClain. Findings suggest that among the most physically active women younger than 65 (women who reported getting about an hour a day of moderate physical activity) cancer was 47% rarer for those who got at least seven hours of nightly sleep. Thus, McClain and colleagues believe that physical activity and sleep play an important role in reducing cancer risk. Those findings held regardless of other cancer risk factors.

This study which was reported at a meeting of the American Association for Cancer Research has left researchers quite surprised and curios about how these two factors work together. The study involving 5,968 women in Maryland confirmed previous findings that people who do regular physical activity are less likely to develop cancer. But nothing was known about the importance of sleep when it comes to preventing cancer. Sleep experts say chronic sleep loss is associated with obesity, diabetes, high blood pressure, stroke, cardiovascular disease, depression, cigarette smoking and excessive drinking.

McClain himself said it is unclear exactly how getting too little sleep may make one more susceptible to cancer. "Getting adequate sleep has been long associated with health," McClain said.