Why Do We Say "Hit the Sack"?

After a long day, you might say you’re going to “hit the sack.” But before we tucked into cozy duvets on plush pads, the phrase had a much more literal—and far less comfortable—meaning.

Today, it’s an easy, almost throwaway way to say you’re heading to sleep. But once upon a time, a “sack” wasn’t just slang—it was the bed itself. Filled with straw or hay, these early sleeping surfaces were a far cry from the modern mattresses we’re used to now.

So how did we go from rough, makeshift bedding to a casual expression we still use today? And why has this old-fashioned phrase stuck around long after its literal origins faded away? Here’s a closer look at where “hit the sack” came from—and why it still hasn’t been put to bed.

The Literal Meaning of “Hit the Sack”

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“Hit the sack” and the similar idiom “hit the hay” are most commonly used to mean that someone is ready to go to bed. The expressions date back to a time when mattresses were made up of fibrous materials rather than memory foam, making the “sack” or “hay” a literal place to sleep.

Today, the phrases are used casually in conversation as a simple way to say someone is going to sleep. While once tied to more literal sleeping arrangements, they’ve since evolved into familiar slang that signals it’s time to turn in for the night.

From Straw Beds to Sailors’ Slang

Across the ages, people slept on simple bedding made from hay, straw, and grass stuffed into sacks, a practice that dates back to ancient Egypt and continued through the 19th century. Centuries of “sacks” cemented the word as a slang term for bed, and by 1825, sailors were already using it in everyday language, including phrases like “sack duty” to refer to sleeping.

While “hit the sack” and “hit the hay” are often used interchangeably now, “hit the hay” came first, appearing decades earlier in the early 1900s, according to the Oxford English Dictionary. Fast forward to the 1940s, and the idiom “hit the sack” as we know it today took hold thanks to American soldiers in World War II, who adapted military slang for sleeping bag to mean going to bed. One of the earliest recorded examples appears in a 1944 war journal by U.S. Navy sailor Thomas D. Schreck, who wrote, “Got the ship slowed down because of a sub warning. Hit the sack at 21:00.”

Why We Still “Hit the Sack” Today

Even as the phrase evolved beyond its literal origins, its usefulness never really went away. “Hit the sack” fits neatly into casual conversation, offering a quick way to signal that it’s time to sleep without overthinking it. And unlike more formal phrases like “retire for the evening” or “turn in”, it carries a relaxed, almost playful tone that makes it feel natural in everyday speech.

In fact, saying you’re going to “hit the sack” can even suggest that you’re especially sleepy or exhausted—so tired, in fact, that you could fall asleep on even a straw-filled sack. Though bare-bones bedding is largely a thing of the past, the expression continues to evoke the same idea: calling it a night and getting some rest.

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