When you feel like you're experiencing an earthquake while you're asleep, it's likely due to a condition called sleep myoclonus. Myoclonus is defined as involuntary muscle jerks and can occur while you're awake or asleep. Sleep myoclonus is more likely to happen if you're sleep-deprived, and can also be brought on by stress, anxiety, medications, and even some medical conditions. The good news is that sleep myoclonus is usually harmless, and doesn't require any treatment. If you're concerned about your sleep myoclonus, or if it's keeping you from getting a good night's sleep, talk to your doctor.