What is hit the hay?

"Hit the hay" is an informal idiomatic expression that means to go to bed or to go to sleep. The phrase is often used when someone is tired and ready to end their day by going to sleep. The origins of the expression date back to the late 19th and early 20th centuries.

In the past, mattresses were often stuffed with hay, especially in rural areas or among those who couldn’t afford more expensive materials. Before going to bed, someone might literally "hit the hay" to soften the mattress or to fluff it up before sleeping. Over time, this physical action associated with bedtime evolved into the idiom we use today. Other similar expressions include "hit the sack," which has a comparable meaning and origin, as it refers to beds made from sacks filled with hay or straw.