Have a long face

Origin

The image of a 'long face' for sadness isn't about physical dimensions, but rather the visible effect of despair on one's expression. When grief or disappointment takes hold, the muscles of the face can relax and sag, the corners of the mouth turn down, and the overall impression is one of a drawn-out, solemn countenance. This visual metaphor for sorrow was well-established by the 18th century, drawing on the universal human experience of seeing inner unhappiness mirrored in a person's drooping features, as if the weight of their sadness had literally stretched their face.