With the holidays quickly approaching, you might be wary of shelling out extra cash to replace your mattress, but neglecting to get a new mattress when yours has outlived its shelf life can be detrimental to your health. Losing out on sleep can contribute to weight gain, memory loss, and even more serious health risks like stroke, heart attack, or cancer.Here are three ways to tell if you need a new mattress, along with tips for finding fantastic mattress deals, so you can sleep easy this...