Feeling your heart beating in your chest when lying down is a common experience known as heart palpitations. These palpitations can feel like fluttering, racing, pounding, or even irregular heartbeats. They often become more noticeable at night or when lying down because there are fewer distractions and the body is more relaxed, making one more aware of sensations like heartbeat. Common causes include stress, anxiety, caffeine consumption, certain medications, and sometimes the position in which one sleeps. For example, sleeping on your side or back can increase pressure inside the body, making the heartbeat more perceptible. In many cases, these palpitations are harmless and not related to any underlying heart condition. However, if palpitations are frequent, accompanied by chest pain, dizziness, shortness of breath, or fainting, it is important to seek medical evaluation as these could be signs of heart rhythm disorders or other heart issues. In summary, feeling your heart beat in your chest while lying down is often normal and related to factors like relaxation, body position, and lifestyle, but persistent or severe symptoms warrant medical attention.