Your brain can’t get enough oxygen and nutrients if a blood vessel bursts or is blocked by a clot. That causes a stroke, and it can make one side of your face -- including eyelids -- droop. Get help within 3 hours of first symptoms. Watch out for numbness/weakness, or trouble speaking, seeing, or walking.
To cut your odds of a stroke, exercise and eat well. Work with a doctor to manage diabetes, cholesterol, and blood pressure. And if you smoke, quit.