To hit the hay is to go to bed. Time to hit the hay, ready to hit the hay, going to hit the hay early.
It comes from mattresses that really were stuffed with straw or hay. To hit the hay is casual and friendly, and nobody says it in writing.
1phrasehit the hayTo go to bed.
“I am going to hit the hay before midnight for once.”
hit the hay is a phrase.
Also accepted in games: hit the sack
Practised in Idioms