The common reasons for children waking up with swollen eyes are mosquito bites, drinking too much water before going to bed, eye diseases, kidney diseases and so on. 1. Mosquito bites: If mosquitoes bite your child’s eyes at night, it will cause eye swelling and pain. 2. Drinking too much water before going to bed: If the child drinks a lot of water before going to bed, the child’s kidneys have poorer excretory function, which will cause edema of the eyelid on the second day. 3. Eye diseases: Bacterial infections and other causes can cause conjunctivitis, chalazion and other eye diseases, which are manifested as swelling of the eyes. 4. Kidney disease: Acute glomerulonephritis, nephrotic syndrome and other kidney diseases can also be manifested as swelling of the eyelids. Children waking up with swollen eyes may also be caused by other reasons, should go to the hospital in a timely manner to identify the causes and targeted treatment.