When you wake up in the morning why do your bones crack?

When you wake up in the morning, your bones may crack due to the release of gas bubbles in the synovial fluid of your joints, a phenomenon known as cavitation. During sleep, your body is relatively still, and the pressure changes in the joints can lead to this gas release when you move. Additionally, stiffness from inactivity overnight can cause ligaments and tendons to tighten, leading to cracking sounds as you stretch or move. These sounds are generally normal and not a cause for concern unless accompanied by pain.