Idiom B2

Let sleeping dogs lie

Do not disturb a situation that is currently peaceful or resolved

Meaning

Let sleeping dogs lie — To leave a situation that is currently calm or resolved without disturbing it, because bringing up old issues could reawaken conflict or cause fresh problems. Literal: do not wake a sleeping dog, which might then bite or bark. Figurative: do not raise old grievances, disputes, or sensitive issues that have settled down.

Origin & History

This idiom is one of the oldest in English. A version of it appears in Geoffrey Chaucer's Troilus and Criseyde (around 1374): "it is nought good a slepyng hound to wake" — meaning it is unwise to wake a sleeping hound. Versions of the same proverb have existed across many European languages, suggesting it captures a universal piece of wisdom about the dangers of disturbing settled disputes.

The exact modern phrase "let sleeping dogs lie" became common in English during the 19th century. It was used by writers including Sir Walter Scott. The idiom is based on the very practical observation that dogs which are asleep pose no threat — but if you wake them, you risk a bite. Applied figuratively, it counsels restraint: if a conflict or problem has gone quiet, leave it that way.

Example Sentences

SentenceContext
My sister and I had an argument last year, but it's all calm now — I'm going to let sleeping dogs lie.Personal relationship, past conflict
The lawyer advised his client to let sleeping dogs lie rather than appealing the verdict.Legal advice, risk management
There's an old salary dispute in the team — best to let sleeping dogs lie unless someone raises it.Workplace, team management
He decided to let sleeping dogs lie and never told his friend what he had overheard.Friendship, discretion

How to Use It

The idiom is used to give advice or to explain a decision not to revisit an old problem. Common forms: let sleeping dogs lie (advice), I decided to let sleeping dogs lie (explaining a past decision), it's better to let sleeping dogs lie (general wisdom). It is neutral in register — appropriate in everyday speech, advice columns, journalism, and semi-formal writing.

Common Mistakes

Mistakes to Avoid

Let sleeping dog lie — there is no reason to revisit it.

Let sleeping dogs lie — there is no reason to revisit it. — Always 'dogs' (plural), not 'dog'.

We should let sleeping dogs lie and take action immediately.

We should let sleeping dogs lie — the situation has calmed down. — The idiom means do NOT take action; it advises leaving things alone.

Let sleeping dogs lay on the ground.

Let sleeping dogs lie. — The verb is 'lie' (to be in a resting position), not 'lay' (to place something down).

Similar Idioms

The writing is on the wall Bite the bullet Sit on the fence Face the music All Idioms →

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Frequently Asked Questions

What does "let sleeping dogs lie" mean?
"Let sleeping dogs lie" means to leave a situation that is currently calm or resolved without disturbing it, because bringing up old issues could reawaken conflict or cause fresh problems.
Where does "let sleeping dogs lie" come from?
The idiom is one of the oldest in English, appearing in Chaucer's Troilus and Criseyde (c. 1374) as 'it is nought good a slepyng hound to wake'. Versions exist in many European languages. The modern English form became common in the 19th century.
Can you give an example of "let sleeping dogs lie" in a sentence?
"My sister and I had an argument last year, but it's all calm now — I'm going to let sleeping dogs lie and not bring it up again."
Is "let sleeping dogs lie" formal or informal?
The idiom is neutral. It is common in everyday speech, advice columns, journalism, and workplace communication. It is generally avoided in formal legal or academic writing, where 'refrain from raising past issues' is preferred.
What CEFR level is "let sleeping dogs lie"?
B2. The figurative structure — dogs representing old conflicts — makes it slightly more advanced, but it is a very well-known idiom that upper-intermediate learners should understand and be able to use actively.
What are common mistakes with "let sleeping dogs lie"?
Common errors: using 'dog' (singular) instead of 'dogs' (plural); confusing the meaning (it advises NOT taking action, not encouraging action); and using 'lay' instead of 'lie' — the verb 'lie' (to rest) is correct here.
Is this idiom advice or a description?
It is advice. It is typically used to advise someone NOT to stir up a situation that is currently peaceful, or to explain why someone chose not to revisit an old problem.
What idioms are similar to "let sleeping dogs lie"?
Similar idioms: 'leave well enough alone' (don't try to improve something that works), 'don't rock the boat' (avoid causing trouble in a stable situation), 'water under the bridge' (something from the past that should be forgotten), and 'if it ain't broke, don't fix it'.
Can "let sleeping dogs lie" be used in writing?
Yes, in both spoken and written English. It works well in journalism, opinion pieces, advice writing, and narrative fiction. Its age and familiarity make it feel natural in a wide range of contexts.
How do I practise idioms like "let sleeping dogs lie"?
Use LexFizz's Flash Cards and Flip Tiles. Think of a real situation where this advice applies — a disagreement that has calmed down — and write a sentence using the idiom in that context to make it memorable.