Counting sheep

Sheep on a paddock

Counting sheep is a mental exercise used in some Western cultures as a means of putting oneself to sleep.

In most depictions of the activity, the practitioner envisions an endless series of identical white sheep jumping over a fence, while counting them as they do so. The idea, presumably, is to induce boredom while occupying the mind with something simple, repetitive, and rhythmic, all of which are known to help humans sleep.

Although the practice is largely a stereotype, and rarely used as a solution for insomnia, it has been so commonly referenced by cartoons, comic strips, and other mass media, that it has become deeply engrained into popular culture's notion of sleep. The term "counting sheep" has entered the English language as an idiomatic term for insomnia. Sheep themselves have become associated with sleep, or lack thereof.