Does Hit the Hay mean go to sleep?

Yes, the phrase "hit the hay" means to go to sleep. It is a colloquial expression that originated in the United States in the 19th century. The term "hay" refers to the dried grass that was commonly used as bedding for horses and other livestock. When someone went to bed, they were said to be "hitting the hay" because they were lying down on the same material that their animals slept on. Over time, the phrase came to be used more broadly to mean simply going to sleep, regardless of the type of bedding used.