How do we identify rest? It may be snoring, heavy breathing, stillness, or the simple action of closing one’s eyes. More importantly, how do we visualize and communicate it in writing – an action surrounding silence and dormancy? Often in a trio and varying capitalizations, we’ve associated “Z” with sleep through illustrations, onomatopoeias, and everyday writing. Just as 'X' and 'O' are linked to hugs and kisses, it seems that these symbols have existed long without origin.

The formation of ‘Zzz’ does, however, have a historical association with its meaning. Henry David Thoreau, an American essayist and naturalist, has been credited with the birth of this alphabetical triad. The pop culture reference can be traced back to his writings, Journal 1837-1846, where he specifically quotes, “The dry z-ing of the locust is heard….”. His career in naturalist writings and philosophy helped form the way we write the hums or snores of certain beings, specifically insects, for the time. Over the years, “z-ing” merged with human snoring, interacting this type of hum with human nature.

It wasn’t until the 20th century that “Z” was used more frequently in media as a representation of sleeping, specifically illustrations and speech bubbles in comic strips. The usage can be seen as early as 1903 in a comic strip called The Katzenjammer Kids by Rudolph Dirks, a series beginning in 1897.^ Here, the captain character is seen dozing off in a hammock, a string of “z-z-z” flowing from his beard as he rests. Audiences may read the bubble as his heavy breathing or soft snoring, given the use of hyphenation and lowercase letters. This variation is one of many ways we might see sleep written in media, a portrayal cemented by 20th-century illustrations.

Sleep and snoring became virtually interchangeable in comics, and a new standard was agreed upon. The “Zzz” symbol was widely recognized beyond its alphabetic stance with time; colossal letters for a noisy sleeper, dainty, modest trails for a peaceful slumber. Excessive strings of sleep down to a lone “Z” all shared the same sentiment of snooze. The American Dialect Society formalized the phrasing in 1918, and popular idioms soon followed, such as “catch some Zs.”

This expression of slumber may have an origin, but the question remains, why? Many speculate it may be due to the correlation between snoring and the word “snooze,” which was introduced to the English language in the late 1700s. The sound is largely attributed to the sawing of wood accompanied by the “Z” shaped edge of the tool. Originally, characters in media were shown to saw through logs as an indication of their rest. This action later meshed with the appearance of the letter, which took over its meaning in time.

While not everyone knows how it came to be, the signifying “Z” is recognized globally as a marker of sleep. Its onomatopoeic influence stands the test of time, entwining itself with a good night’s sleep for over one hundred years and counting!

^ https://en.wikipedia.org/wiki/The_Katzenjammer_Kids