nap problems

I become tired sometimes and decide to take a nap.

Sometimes, the result is this:

Other times, the result is this:

Scientifically, the best amount of time for a nap is 15-20 minutes, 1.5 hrs, or a full night. Anecdotally, this is what happens when I nap:

People are always coming up with those rhymes to remember what not to do (i.e. beer before liquor). I always thought they were pretty mediocre. Here's an equally mediocre one for sleeping: