Why do I wake up with puffy eyes?

Puffy Eyes. Puffy or swollen eyes can be caused by fluid retention, stress, allergies, hormone changes, and other factors. Other times we get puffy eyes after sleeping. This can be caused by too much sodium in the diet, which causes water retention. Puffy eyes can also be caused by lack of sleep or excessive alcohol intake. http://www.eyehealthweb.com/puffy-eyes/
Numerous reasons. Could be many things from sinus problems to kidney problems. See your eye doctor first.