Next, lie down on your bed and really take notice of how you're really feeling. Does the bed feel more like a wooden board? Haex says that if it feels firm, you're likely only supported under your shoulders and hips, leaving your spine unsupported and unaligned. "Alternately, if it's too soft, it's like sleeping in a hammock," he adds. And while that may sound lovely, having a sunken spine and unsupported shoulders and hips makes for a far less enjoyable snooze. Whether your bed is too firm or too soft, both instances can lead to discomfort and interrupted sleep -- and may also mean it's time for you to buy a new mattress.