Zzzzzzzzzzzzz.... afternoon sleepytime

In the summer, I do most of my work from home (and get to set my own hours), which is a good thing because home or not, around 2pm I start feeling like I can barely stay upright, I'm so dang sleepy.  I sometimes have this happen during the rest of the year, but someting about the hot weather (I live in Texas, so we're talking HOT) really takes it out of me.

Does anyone else get the afternoon sleepies?  What do you do to get through them?  Or should I give up and just take a nap?