There’s nothing wrong with taking a rest. Lay down and nap. Sleep in on Saturday some. It’s ok.
As long as your responsibilities are taken care of (or atleast covered for you), don’t feel guilty. It’s true, if you’re tired and running on no or negative energy, make some.
Go ahead, close your eyes, play a meditation or some chill music and drift away for a little bit- you’ll be amazed what even twenty minutes can do to your mood!