Never try to think when you are tired. Your mind will deceive you and you'll conclude the most preposterous things. It's like being drunk-I think. I've never been drunk before.
Anyways, avoid trying to delve into anything deep, important, or noteworthy when you are half asleep. It's like there's a little devil inside you trying to trick you into picking the wrong answer while you are convinced that it is right. Make sure you go to sleep and get a good night's rest.
This probably all sounds like nonsense, and maybe it's because it is Friday night. I'm writing nonsense at the end of a long week, and at the end of a long day. But it's not. I give you solid advice not to push the envelope when you're so tired you're not even sure if it's an envelope you have in hand.