The origin of conveying sleep with "zzzzzz" in comics can be traced back to the early 20th century, around the 1910s and 1920s. This comic convention is commonly known as "snore lines" or "sleep lines."
The usage of "zzzzzz" to indicate sleep in comics likely emerged as a visual onomatopoeia to represent the sound of snoring. The letter "z" was chosen because it mimics the sound of a snore, creating a simple and recognizable visual representation of sleep or a sleeping character.
One of the earliest known instances of using "zzzzzz" in comics is in the comic strip "Krazy Kat" by George Herriman, which debuted in 1913. The character Ignatz Mouse is often seen sleeping with "zzzzzz" emanating from him. This usage became popular and was subsequently adopted by other comic artists and writers, becoming a standard way to depict sleep in the medium.
Over time, "zzzzzz" has become a universal shorthand for sleep in comics and is now a widely recognized visual symbol across various cultures and languages. It has since become a staple element in comic strips, comic books, and other forms of visual storytelling to represent slumber or dozing off.