The word 睡着 is formed by combining the character 睡, which depicts a person (目 as an eye) resting by a vertical element (垂, suggesting drooping), meaning "to sleep", with the character 着, which here functions not as an independent word but as a grammatical marker attached to the verb. This combination creates a new, single concept where the action of sleeping (睡) achieves and enters a resulting state of being asleep, with 着 indicating the attainment and continuation of that state, effectively turning the verb into a state of completion. It is a direct and intuitive semantic layering where the second character modifies the first to capture a specific moment of transition and resulting condition.