You fall asleep on your... belly
Potential problem: To breathe easily, you have to twist your head to the right or left, which can strain your neck.
Easy adjustment: Start off the night lying on your side with a pillow between your knees. Or try a body pillow to lean into as you sleep. Both will keep your spine and neck more naturally aligned.
You fall asleep on your... back
Potential problem: If your head is elevated too high (and your chin points down to your chest), your spine may curve forward, creating tension in the shoulders and upper back.
Easy adjustment: Sleep with a flatter pillow -- and put another one under your knees to prevent your lower back from arching, which can also cause pain.
You fall asleep on your... side
Potential problem: Your middle can dip toward the mattress and put pressure on your lower back.
Easy adjustment: Put a rolled towel between your waist and the bed, positioning it under the fitted sheet.