When a patient wakes up with a rapid heartbeat, the following diseases should be considered: 1. Organic heart diseases, such as coronary heart disease, unstable angina, myocarditis, pericarditis, heart valve disease, endocarditis, hypertrophic obstructive heart disease or hypertensive heart disease, can cause arrhythmia, resulting in a rapid heartbeat when waking up. 2. Poisoning or metabolic disorders with acid-base imbalance can also cause a rapid heartbeat when waking up. 3. 3. endocrine system diseases, such as hyperthyroidism and hyperadrenocorticism, can also cause tachycardia when the patient wakes up. 4. cardiac neurosis, such as plant nerve dysfunction, can also cause tachycardia when the patient wakes up.