DON'T THINK WHEN YOUR ARE TIRED !!!
Don't even give a try !
Don't try to solve a problem, to make any important decision, to have an argument with someone... Actually, when tired, just take it easy, protecting yourself and indulging yourself the best your can, to avoid a worst situation. Kind of low profile, consciously. My best teacher ? My cat !
You're a bit tired ? REST ! Relax yourself, even 5 minutes, but really !
Then GO TO BED EARLY (with a light reading, kids comics or boring Classic Novel).
Because the morning after : WELCOME BACK TO THE WORLD, MY FRIEND ! WITH A BIG SMILE TO LIFE !