Why do naps make me feel depressed?

Factual Questions
1

Whenever I take a nap, I end up feeling incredibly depressed rather than grumpy like most people. Worse, post-nap I’m unable to really do anything - I feel unable to concentrate or do anything but sort of mope.

What’s going on? Is this a recognized phenomenon?

2

It might have to do with how serotonin and melotonin get regulated during sleep (as explained here). It could be either that you’re sleeping an inappropriate amount of time, thus disrupting your serotonin regulation, or you’re confusing your “body clock”.