Swelling of feet at night while sleeping may be caused by increased venous blood pressure in lower limbs, organic diseases, overwork, overweight and so on. 1. Increased venous blood pressure in the lower limbs: when older patients with varicose veins stand for a long time, it will cause increased venous static blood pressure in the lower limbs, resulting in edema of the lower limbs when sleeping at night. These patients can be relieved with a little rest. 2. Organic diseases: when the patient suffers from kidney disease, cardiac insufficiency, liver insufficiency, hormone secretion abnormality or taking certain drugs, it can also cause foot swelling at night. 3. Excessive exertion: patients who are overworked, over-exercise, heavy physical labor can also cause increased venous blood pressure to form swollen feet at night. 4. Obesity: when the patient is too obese, it can also cause swelling of the feet at night. There are many other reasons for the swelling of the feet at night, it is recommended that the relevant patients seek timely medical examination to clarify the cause and targeted treatment and treatment.