Dormir comme un sabot

Literally: To sleep like a spinning top

Example: “Après la randonnée, les enfants ont dormi comme des sabots.” — After the hike, the kids slept like logs.

English equivalent: To sleep like a log

Origin: Not the wooden shoe. Before sabot meant footwear — a sense that appears only at the end of the 15th century — the word existed from the end of the 12th for a spinning top, conical below and cylindrical above, that children whipped along with a lash. The connection to sleep is what the top does at full speed: it appears perfectly still, and on some surfaces it hums faintly. French said le sabot dort, the top is sleeping. Villon has the expression in the 15th century, and the only reason it survives is that everyone still thinks they know what a sabot is.