According to a new study, lack of sleep is linked to more aggressive breast cancers. The researchers surveyed more than 400 post-menopausal women with breast cancer, and found that those who had slept an average of six hours or fewer the past couple of years had more tumor recurrence.

Of course, there are many other benefits to being well-rested, from improved memory to decreased risk of heart attacks—and of course, a smaller waistline. They don’t call it beauty rest for nothing!

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