To prevent puffy swollen eyes after sleeping, you should not drink too much water within 3 hours before sleeping. Don't eat food that is too salty or hot which will make you drink more water before sleep and then lead to puffy swollen eyes the next morning. You'd better sleep with face up not down because when you sleep with face down, the water will accumulate around your eyes to cause puffy swollen eyes. What's more, wash your face with hot water before sleep can help promote blood circulation, thus it can prevent puffy swollen eyes when you wake up the next morning.
I know some ways that may help you to prevent puffy swollen eyes.
First of all, you shall sleep enough.
Second, you shall avoid or at least limit the amount of salt in your diet.
Third , drink more water.
Four, wash your face before going to bed.