Waking up with swollen feet can be caused by over-activity, nephrotic syndrome, right heart failure and other diseases. 1. Over-activity: If you have recently walked or stood for long hours during the day, resulting in obstruction of venous return to the lower extremities, you will be prone to waking up with swollen feet to a certain extent. 2. Nephrotic syndrome: the cause of the disease is still unclear, but studies have shown that it may be related to genetics, viral infections, immune function impairment, and drugs, such as antibiotics, non-steroidal anti-inflammatory drugs, antihypertensive drugs. Typical symptoms are large amount of proteinuria, edema, hyperlipidemia, hypoproteinemia, which can be manifested as edema of the lower limbs and ankles, so patients will wake up with swollen feet. 3. Right heart failure: the main cause of this disease is myocardial lesions, such as dilated cardiomyopathy, myocarditis, etc., followed by overloading of the heart, which is related to pulmonary embolism, mitral valve closure insufficiency and other diseases. Generally, patients with more serious conditions will have lower limb edema, which can be manifested as swelling of the feet when waking up from sleep, and may also have ascites, hepatomegaly and other symptoms. 4. Other: clinically, we can also consider high blood pressure, varicose veins of the lower extremities, gout and other diseases. It is recommended that patients who wake up with swollen feet go to the hospital in a timely manner, complete the examination, identify the specific causes and follow the doctor’s instructions for treatment.