Idiom
Hit the sack
By EasySay. Published . Updated .
Hit the sack means to go to bed.
A sack is an old word for a mattress filled with straw, so the picture is falling onto the bed. People say it when they are tired: “I am going to hit the sack.” It is casual and friendly, for family and friends, not for a formal letter.
Written for EasySay, in our own words.
In short
- AvoidIt is casual, so do not write it in a formal email.
- Or sayHit the hay
Hit the sack: what it is, and what it is not
- IS
- Going to bed, usually because you are tired.
- IS
- Cambridge and Longman label it informal, and Longman marks one sense old-fashioned.
- IS NOT
- About falling onto a sack: it means going to bed, usually because you are tired.
- DEPENDS
- Longman gives “hit the hay” as a form marked American English.
- DEPENDS
- Longman marks “hit the hay” as American English and labels “hit the sack” informal.
Meaning: To go to bed, usually because you are tired.
How do people say it?
- In conversation:
I am so tired. I think I will hit the sack early tonight.
- At work:
Night shift done. Time to hit the sack before the sun comes up.
Check yourself
What should I know?
The words say
To fall onto a sack, a mattress stuffed with straw.
It really means
To go to bed and sleep.
What do dictionaries say?
- In Australia
- Cambridge and Longman label it informal, and Longman marks one sense old-fashioned. The dictionaries we checked give it no Australian label, so it is general English, not only from Australia.
- In the UK
- Longman gives “hit the hay” as a form marked American English. The dictionaries we checked give it no British label, so it is general English, not only from the UK.
- In the US
- Longman marks “hit the hay” as American English and labels “hit the sack” informal. The dictionaries we checked give it no American label, so it is general English, not only from the US.
What mistakes should I avoid?
- It is casual, so do not write it in a formal email. “Go to bed” is the plain choice.
- Say “hit the sack”, not “hit a sack”. The words stay the same.
- It means going to sleep for the night. Do not use it for a short rest on the couch.
The picture is old farming life, when a mattress was literally a sack stuffed with straw or hay. At the end of a long day the worker fell onto it whole, boots off and cares down. The sack took the weight with a soft thump.
“Hit” keeps that tired fall: you do not climb into bed gracefully, you land on it. The straw is gone from modern beds, but the thump of a long day is still in the words.
It belongs to the small family of bedtime phrases, and each has its own hour. “Call it a day” ends the work, often at dusk; “hit the sack” ends the person, often near midnight.
Its true opposite is “burn the midnight oil”, the choice to stay up and work while others sleep. Put the three on one line, from dusk to midnight to the small hours, and you have the whole evening in three idioms. That line is worth memorising as one picture.
Tone is the only trap. The phrase is warm among equals: family, friends, teammates after a late shift. It turns cold in the wrong mouth, because tiredness can sound like boredom.
Telling a host “I will hit the sack” at nine in the evening may read as rude, whatever you mean. Add the reason and the thanks, and the same words land softly. For example: “The flight was long, so I will hit the sack; thank you for a lovely evening.”
What else can I say?
- Hit the hay The older cousin; same meaning, same tone.
- Go to bed A plain phrase.
- Turn in A little formal; fine in writing.
More idioms
- Burn the midnight oil To work or study late into the night, often to meet a deadline.
- Call it a day To stop working for the day; to finish.
More examples
- In a text:
Long day. Hitting the sack now, talk tomorrow.
Questions people ask
Is “hit the hay” the same?
Yes. Hay and sack both point at the old straw mattress. The two phrases share the meaning and the casual tone.
Can I write it in an email?
Only a casual one to someone you know. In formal writing, “go to bed” or “rest” is safer.
What is the opposite?
“Burn the midnight oil” means staying up late to work. The two make a neat pair for sleep and no sleep.
Sources and dates
- EasySay's own writing for the idioms, EasySay. Licence: original writing for EasySay. Checked .
- Cambridge Dictionary: usage labels, Cambridge University Press & Assessment. Licence: our own words, from the facts in the source. Checked .
- Longman Dictionary of Contemporary English: usage labels, Pearson Education. Licence: our own words, from the facts in the source. Checked .
Cite this page
EasySay. "Hit the sack". https://easysay.org/idioms/hit-the-sack. Last updated 23 October 2026.
https://easysay.org/idioms/hit-the-sack