Tired is when you find out if your manners were real or just energy.

Politeness at full charge is easy and tells you very little. What counts is what happens when you have nothing left, because courtesy then has to come from habit rather than effort. Anyone can be pleasant after a good night of sleep. Being decent on four hours is the version other people actually rely on.

Work out which manner you drop first when you are exhausted: the greeting, the thank you, the tone at home. Hold that one specifically the next time you are wrecked. One is enough to change how the evening lands for everybody else.