Idiom:  night and day


Idiom:  night and day / (like) night and day

  1. all the time; continually
  2. used to describe a clear change or difference between two things

Notes:  When using "night and day" to talk about striking differences, we can also use the expression, "day and night."  While the expressions can be used interchangeably, "day and night" is more frequently used to show that something got worse whereas "night and day" shows something got better.

When using these expressions to talk about differences, we often precede the expression with "like."

Example sentences

All the time/continually:

— You’re on Facebook night and day, why don’t you take a break?

— Our neighbors play loud music night and day and just laugh at us when we ask them to turn it down a little.

— I’ve been working night and day to try to complete the project by the deadline but I still think I’ll need two more weeks to finish it.

— We've been working on the proposal night and day for the past week and still aren't finished.

— After writing night and day to finish the first draft of my novel, my computer died and I didn't back it up anywhere.

A clear change or difference between two things:

— Your grades are like night and day from last semester—congratulations on making the honor roll!

— She started the season with just one win in her first ten matches but her performance in the second half was like night and day, with 30 matches and three tournament wins.

— Now that we've doubled the police force, we hope the number of violent crimes will be night and day with last year.

— Since you lost 100 lbs your appearance is night and day from before.

— I'm so glad we had the report edited. The difference is night and day.


  • round the clock
  • poles apart

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