Just woke up. Heart racing. What's going on?

Many factors can cause rapid heartbeat, this is the performance of tachycardia, may be caused by nightmares, or is caused by too much, may also be nervous, emotional excitement caused by rapid heartbeat, or heart disease caused by rapid heartbeat. If it is often repeated to do ECG and other related tests, to do myocardial enzyme examination, cardiac ultrasound examination, X-ray examination, if it is not found to do further examination. When the heartbeat accelerates, the patient should be quiet, do not need emotional excitement, and rest properly. If it is physiological heartbeat, sleep will improve.