CLEVELAND, Ohio -- Researchers say they have linked a lack of sleep to more aggressive breast cancers.
It's one of the first studies showing insufficient sleep may raise the risk of recurrence in older women.
Data on over 400 breast cancer patients revealed women who averaged less than six hours of sleep a night before their diagnosis had more aggressive tumors than women who slept longer.
And, while that correlation was strong in post-menopausal women, there was no such link in younger breast cancer patients.
This study was led by researchers at Case Western Reserve University and published in the
August issue of 'Breast Cancer Research and Treatment'.