The ordinary courtesy you offer when tired is part of the life other people share with you.

Manners at your worst hour are the ones people actually experience. Anyone can be gracious when rested, but what your household or your colleagues live alongside is how you speak at the end of a long day, and that tone becomes the weather of the place whether or not you meant it to. Tiredness explains a sharp reply without cancelling its effect.

Pick the hour when you are usually most depleted and choose one small courtesy to keep through it. Greeting someone properly, saying thank you, not answering with a sigh. You do not have to be cheerful, only recognisable as someone another person is glad to live near.