Video narration
Why do your eyes keep closing when you're not sleepy? Your eyes are doing useful work. When your eyelids meet, they spread tears-the wetness your eyes make-across the front of your eyes. This thin layer helps keep your eyes moist and comfortable. A blink is more than a quick close; it's a little bit of care. Now imagine a speck of dust drifting near. Your eyelids can close like a shield, helping keep dust and tiny bits away. They don't stop every speck, but they give your eyes protection. And you don't have to plan every blink. Your eyes often do it automatically, while you're thinking or looking around. You can blink on purpose, too. So, why do your eyes blink when you're not sleepy? To spread tears, keep your eyes comfortable, and help protect them from dust, even when you're not thinking about it.