expression

a wake-up call

an event that alerts people to a problem

In more detail

1. (noun) a phone call or alarm set to wake someone up at a specific time

2. (idiom) an event or experience that makes someone suddenly realize they need to change something important in their life

Examples

1. I need to set a wake-up call for 6 a.m. tomorrow morning.
2. Failing the exam was a wake-up call that I needed to study harder.

How to use a wake-up call

As a literal noun, it refers to a scheduled alarm or call to rouse someone from sleep. More commonly today, it is an idiom meaning a sudden realization that forces significant personal change or reassessment, often after a crisis, failure, or concerning event. The tone is typically serious and implies that ignoring the message was previously possible but is now impossible.

Common phrases

serve as a wake-up call
a much-needed wake-up call
receive a wake-up call
deliver a wake-up call to

Synonyms

reality check · warning sign · eye-opener · turning point · alarm bell

A common mistake

Learners sometimes treat 'a wake-up call' as entirely literal when the context is clearly metaphorical, or conversely assume all uses are idiomatic when a speaker might mean an actual morning alarm.

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