Slow heart rate after waking up may be due to physiological phenomenon, heart disease, hypothyroidism and other reasons. 1. Physiological phenomenon: normal people sleep at night when the vagus nerve tone increases, after waking up the sympathetic nerve is still in a state of inhibition, will cause the heart rate to slow down, the heartbeat is weaker, this is a physiological phenomenon. 2. Heart disease: slow heart rate after waking up may be caused by pathological sinus node syndrome, atrioventricular block and other diseases, the heart rate may be lower than 40 beats per minute. 3. Hypothyroidism: Thyroid hormone is an excitatory hormone, and patients with hypothyroidism will experience a decrease in thyroid hormone and a low metabolism in all systems, which will result in a slower heart rate and a slower heart rate after waking up. Slow heart rate after waking up is accompanied by other discomforts, and it is recommended to seek timely medical treatment for serious cases.