Why do I get left side chest pain when I lie down at night?

When you lie down, your body’s position can put extra pressure on your chest. This pressure might cause discomfort especially on the left side because that’s where your heart and some muscles lie. One common cause is acid reflux. When you are lying flat, acid from your stomach can move up into your esophagus, causing a burning or aching pain in your chest. Another reason could be musculoskeletal pain. The muscles and tissues around your chest might become strained or irritated when you lie in a certain way.

Although these causes are often not dangerous, it is important to share your symptoms with a doctor, especially if the pain grows worse or you have trouble breathing, so they can help you find the right treatment and improve your comfort at night.